View Full Version : Need help diagnosing engine troubles 2003 X2!!! Long Story.

07-11-2006, 02:28 PM
I have a 2003 Mastercraft X2 with the Predator 350 TBI engine. Ever since I've owned it (about 1.5 years), it has fouled plugs more than I thought a fuel injected engine should. I always attributed a hard starting problem to the plugs being fouled, and always just cleaned them once a month or so and the boat seemed to run better.

The past month or so I've been noticing that sometimes when we stop to change riders, it would take several attempts at cranking the engine to get it to start. It would always turn over, but had difficulty firing.

This past Saturday, it refused to restart at all. We started it on the trailer, took it out and had been idling up to the spot where we usually start riding. We shut it down, I got my gear on, then we tried to restart it it would just crank, but never fire. I pulled the plug wire off of the ignition coil and it would spark to the block while we were cranking. I'm pretty sure the injectors were working too, because we could smell fuel. We had to be towed back to the trailor.

Back home, I rechecked the plugs which seem to be still quite clean from the last cleaning. I hooked up water and attempted to further diagnose the problem. Much to my surprise it fired right up and ran well. So I let it warm up a bit and decided to shut it down and attempt to restart it. Again, it would crank, but not fire. I pulled the flame arrestor off and saw the injectors spray two quick bursts of fuel while a buddy cranked, and then nothing afterwards.

Anyone have any ideas? I'm going to buy a fuel pressure gauge today and make sure I have the pressure listed in the manual. Anything else that it could be?

07-11-2006, 03:14 PM
get a fuel pressure gauge on that engine, sounds like you have a drop in fuel pressure with the engine off.

could be dripping out of one or more injectors
[fuel smell] into the intake causing hard or no starts, or a fuel regulator leaking down.

post more info, is this only a hot restart problem ?


07-11-2006, 03:48 PM
It has only failed to start twice, once on the lake, and once in my driveway, and both times the engine was up to operating temperature. I am going to try again in a day or so to see if it always starts when cold.

07-12-2006, 09:08 AM
I did a real quick test last night in my garage ( I didn't have time to pull it out and hook water up). I attached my fuel pressure gauge and just turned the key on.

The pressure built up immediately to 30 psi, then dropped back to zero one or two seconds later. Is this normal for key on engine off operation? Could this be the fuel pressure regulator leaking like you said above?

Tonight I'm going to pull it out of the garage and get water hooked up so I can monitor fuel pressure while I'm cranking the engine.

07-12-2006, 09:51 AM
Sounds like a leaky injector. Once it pressures up the injectors dump fuel into the manifold. The rich condition is what causes the hard start. Next time it does it try bumping the throttle to about 1/4 (throttle only) before cranking to get some air in there. If it fires right up you have found your problem.

07-12-2006, 09:54 AM
your engine should have a resting fuel pressure when shut off, it's typically lower than operating fuel pressure but dropping to zero is your hot restart problem. a drop to zero overnight is normal however.

you either have a external or internal leak, I'm guessing internal otherwise you'll have a big mess in your boat.

fuel injected engines generally have fuel pressure regulators at the fuel rail and built into the main fuel pump.

if there's a rubber return line from the FPR on the rail you can pinch it off and see if the drop continues.

note: do not try to pinch off a hard plastic or steel return line and some hard plastic lines have a rubber coating on them making them seem rubber, if you're not sure about what is what do not pinch off any lines, you can do permanent damage to the line.

also you might pull the fuel injector rail and see if any of the injectors is leaking down but I'm thinking if your pressure drops that fast it's not a injector, they tend to drip and take time, start with checking or replacing the fuel rail regulator.


07-13-2006, 09:42 AM
Yesterday I pulled her out of the garage and hooked up water to do more troubleshooting. It started and restarted at least 20 times over the course of about 30-45 minutes of testing in the driveway. It never once failed to start.

Fuel pressure does still drop as I described above. Key on ignition off, you can hear the pump run for a few seconds. While it is running, fuel pressure rises to 30 psi, as soon as the pump shuts off it drops back to 0 psi. While cranking, the fuel pressure quickly rises back to 30 psi. If you turn the ignition on and crank immediately, you see no drop in fuel pressure. There is also no drop at any RPM after the engine is running. We tested it with cold restarts, hot restarts, restarts after the key was on and engine off for 5+ minutes, and restarts with the engine cover open and closed and it started 100% of the time.

I inspected the injectors and could find no fuel leaking there. I'm still not sure about the fuel pressure regulator. Since I have hard fuel supply and return lines, I couldn't crimp the return line as mentioned above. I still think that not holding fuel pressure could be a problem, especially if fuel is leaking into the manifold. I might try to find some type of plug for the return fuel line fitting and unbolt and plug it off to see if pressure holds.

I think I read somewhere that you can buy a fuel pressure regulator rebuild kit that has a new rubber diaphram. Anyone heard of this? It might be worth it to just replace that part and hope for the best.

07-13-2006, 10:10 AM
your fuel pressure should not be dropping that fast, you have a problem. does the fuel pressure reg have a vacuum line coming off of it ? if so pull that line and see if there's any fuel in it, there should not be any fuel in that vacuum line.

also you don't need to start your engine to diagnose your fault, just cycle the key and watch the fuel pressure gauge.

can you post some pics of your reg ?

you're so close to fixing your fault, keep at it.


07-13-2006, 11:07 AM
I don't have any actual pictures, but it looks exactly like the one in this picture.


There are no vacuum lines that I can see connected to it. I'm about 90% certain that the fuel pressure regulator is a rubber diaphragm with a spring that is inside the housing that you see on the top right of the picture (just to the left of the injectors, above and in between the two fuel line connections). Perhaps it gets vacuum internally.

07-13-2006, 02:23 PM
pickup a rebuild kit, remove the cover and inspect the diaphragm and where it seats, you'll probably find something visually wrong.


07-13-2006, 05:16 PM

What part of TX you in? If DFW, PM me and I may have a # for you.

07-13-2006, 05:53 PM
First of all, the injectors don't dump fuel once the pressure has been reached. If it did that, they wouldn't use pulse width as the determining factor as to how much gas goes to the intake. The ECM tells the injectors when to open and for how long.

If the fuel pressure gauge only shows pressure without holding the reading, that would explain the drop to zero. If it does hold and it still went to zero, it sounds like it could be the regulator or the fuel return system. Remove the flame arrestor and look at the injectors when you turn the key on. If you see fuel spray, there's a problem. If you don't see spray or dripping, the injectors are probably fine. They could need cleaning, too.

The vacuum fitting at the bottom left of the injector photo is where the MAP sensor connects. It is for a vacuum line and this can become filled with fluid. Check it out.

If it is a pressure issue, try turning the key to ON and let the pump prime, then turn it off and wait for more than 5 seconds. Crank it and see if it starts easier. If the pressure gauge doesn't have a relief valve on it, use a different one. The line has air in it and the test isn't valid. Check the pressure ar key ON, idle, 2000 RPM (under load- on the water) and at WOT. Those are the test points recommended by CM and Indmar. If you crack the throttle and it starts easier every time, it could be an IAC issue. It may be closing too much at key off and needs to be reset or replaced.

Why are you trying to fix a motor that could still be under warranty?

07-13-2006, 11:33 PM
[First of all, the injectors don't dump fuel once the pressure has been reached]: actually this is how CIS injection works, and many diesel injection systems work this way. however txasag99 boat does not work this way.

[Remove the flame arrestor and look at the injectors when you turn the key on. If you see fuel spray, there's a problem. If you don't see spray or dripping, the injectors are probably fine. They could need cleaning, too].

mechanical and electronic injectors can leak at rest causing loss of residual fuel pressure, flooding of one or more cylinders / intake manifold and cause the symptoms described earlier in this thread.
with TBI this is a easy one to inspect as JimN stated.

[The vacuum fitting at the bottom left of the injector photo is where the MAP sensor connects. It is for a vacuum line and this can become filled with fluid. Check it out].

this is a good tip, easy to check and would point to internal leakage and cause the symptoms described.

[If the pressure gauge doesn't have a relief valve on it, use a different one. The line has air in it and the test isn't valid].

FP gauges with relief valves and lines are great for taking fuel samples and safely letting of residual FP after testing but not necessary for taking accurate FP readings, modern fuel management systems will self bleed the system after diagnostics and repairs. however as the engine compartments heat up the main pump is less efficient at this ,also known as vapor lock.

assuming you've installed the FP gauge properly, your instant drop of FP after you have shut the key off is your starting problem and fits all the symptoms you've described.

[Why are you trying to fix a motor that could still be under warranty?]
this is the best question so far, if your boat is under warranty, trained people are being paid and waiting to work on your boat, how cool is that ?

on a safety note, working with high pressure fuel systems great care needs to be taken when disconnecting a charged system. with 30 or more PSI, it's enough to spray across the room, in your eyes, in your boat etc....


07-13-2006, 11:59 PM
CIS and diesel injection don't really apply here, so my reply dealt with the system that does.

The fuel system may be self-bleeding but if there's air in the fuel pressure gauge hose, the pressure won't be accurate. Best to bleed the air out and get the correct reading. Also, every time I have ever taken a fuel pressure reading, I did a fuel quality check, too. It takes about a minute and really saves time later. I like doing the quality check after the boat has been moving and any water in the tank is more evenly distributed. Then, after it sits, I can see if there's any water in it.

One thing I haven't seen any mention of is the idle speed. If it's appreciably higher than 700 RPM, there's a vacuum leak.

The PCV valve(s) should be checked, too.

The MAP hose being filled with gas is more likely to occur on the '94 and '95 boats since they have the MAP sensor hanging lower than the new ones but it's still a possibility.

Nobody mentioned doing a compression check, either. If the plugs are fouling, this should be done. If the compression is bad, the vacuum won't be up to par, either.

07-14-2006, 09:35 AM
I'm the second owner and didn't pay the $450 to transfer the warranty for just a few months.:cry: No offense to any dealers either, but $90-$100 per hour for labor is more than I am willing to pay.

Thanks for the replies guys, I've ordered the fuel pressure regulator rebuild kit (it's cheap < $30) and will start there.

My fuel pressure gauge has a bleeder valve to release any trapped air, so that is a non-issue. I can see no leaking out of either injector with the K.O.E.O, but the fuel is going somewhere thus the quick build of pressure to 30 psi and then drop back to zero.

I'll pull the map sensor loose and check for any fluids in the vacuum hose. The idle speed is normal, well under 700 rpm.

07-14-2006, 09:41 AM
Did you check the pressure with the motor running? The pump should be able to supply more than enough pressure, even at WOT so it should run anyway.

07-14-2006, 09:54 AM
Yup, engine running, pressure is great always around 30 psi at every rpm. Of course this is only in my driveway, so no engine load.

07-14-2006, 10:00 AM
I had this same problem in an 01 X-9 with the MCX. My hot failed restart problem was simply a crimped hose inside the in-tank fuel pump. Once I replaced the entire fuel pump, the problem went away.

07-16-2006, 09:48 PM
Well guys, I got the fuel pressure regulator rebuild kit on Saturday and replaced the regulator diaphragm. The kit also came with all new gaskets for basically the entire tbi injection system, so I replaced as many of those as possible without completely removing the system from the manifold.

I didn't notice any visible problems with the old regulator, so I'm not sure that I've eliminated the problem. It still won't hold fuel pressure with the pump off, so I'm thinking it might be a bad check valve in the fuel pump, or maybe a pinched hose as mentioned above.

I took it out on the lake for a few test runs today, and it ran great and fuel pressure was good under both heavy and light throttle and under load. We were finally able to repeat the hot restart problem after being out for about 4 hours. Unfortuneatly, I wasn't able to check the fuel gauge, as my gf was cranking, and it started on about the 3rd try. I'm thinking that maybe fuel is vapor locking in the supply line since it isn't being held under pressure.

I guess my only option at this point is to order the $500 fuel pump. Seems rediculous to me to spend that for a part that will likely fail again soon. Has anyone considered using an inline fuel pump (like a holley) and just fabbing up some lines to splice it in? Probably would last longer, I notice that tons of these fail.

07-16-2006, 10:41 PM
Did you try turning the key to ON for the priming cycle and them waiting for more than 5 seconds before trying it again, like I suggested before? You could have a crimped fuel line, too. Call MC and ask what they think it could be and get the service history for the boat, which I also suggested before. There may be some kind of history of this problem and if it wasn't fixed during the warranty period, they may cover it for you.

07-20-2006, 01:17 AM
sorry to hear your mini rebuild of the TBI didn't solve your problem, you're on the right track however, you need to have some fuel pressure at rest to resolve your hot start fault. sounds like the repair is going to get more expensive. before buying a pump re-evaluate all your testing methods.


07-20-2006, 11:37 AM
I'm the second owner and didn't pay the $450 to transfer the warranty for just a few months.:cry: No offense to any dealers either, but $90-$100 per hour for labor is more than I am willing to pay.

I guess my only option at this point is to order the $500 fuel pump. Seems rediculous to me to spend that for a part that will likely fail again soon.

How much money are you willing to throw at it before taking it to someone who has the experience and equipment to quickly assess and repair the problem?

07-24-2006, 09:16 AM
1 million dollars, muhhaaahaaaahaaaaa.:purplaugh

07-24-2006, 09:58 AM
If the pump primes to normal pressure, then bleeds off, and the injectors are not leaking, would have to be a faulty check valve in the fuel pump, assuming the regulator is working ok.

07-24-2006, 10:21 AM
My thoughts exactly Gregg, thanks for the positive input. Do you think that the check valve can be replaced without replacing the entire pump?

FWIW, she's been starting fine lately, so if I end up having to replace the pump, I'll probably just live with it for awhile until the offseason when cash and time is more readily available.

07-24-2006, 10:29 AM
Check valve would be built into the pump assembly.

07-24-2006, 11:06 AM
Maybe a long shot, but one other thing I have had problems with from time to time is my idle air control motor. Once a month or so my engine will fire and stall right away. Then will flood pretty easy and I have to neutral the trans and open the throttle a little bit. Once I pull the IAC off and clean the pintle, it works fine for another month or so.

The fuel pressure drop however is still not normal, but, as soon as the engine control module(computer) gets an rpm signal from the distributor, it should turn the fuel pump back on, after its initial 2 sec. prime.

Question... Are u certain you have spark while cranking during the no start?? My 2002 maristar 310 tbi left me in the middle of the lake two weeks ago. Was running around 3000 rpm and just stalled like I shut it off. Checked kill switch first and was ok. Had injector pulse, but no spark. Had a local car quest store send an ignition module out to the marina, they jet skied it out to me and it fired right up. Sometimes ignition modules will fail due to temp. and will work again after they cool a little bit. I seem to remember earlier in the thread you mentioned you had spark, but no injector pulse during cranking. If the pump is running during cranking, you have spark, but no injector pulse, could be a bad injector driver in the engine controller also. Just throwing out some other possible causes for your hard starting.

07-24-2006, 01:32 PM
Hi TxsAg99,
We have a 2003 X2 with the exact same problem you're describing! My mouth gaped as you described every detail of what we have experienced. We are taking it to the dealer this week and will definitely let you know what they find (incase it helps you too). From the sounds of it you are getting closer to finding your problem but it would be highly coincidental if we have the exact same symptoms on the exact same boat but with a different cause.
Thank you for the updates.
Jessica and Eric Coppola (Davis, California)

07-24-2006, 01:42 PM
Make sure the edge of the pullies are level and there isn't s step back on one of them.

These belts glaze and dry out over time and that's the reason they squeal. I've been going through at least one belt every year on my truck and at this point, I think it may be the tensioner that's causing it. Or, it could be the anti-freeze that got on it when a friend "helped" me change my thermostat last winter.

08-04-2006, 12:46 PM
I was hoping to have something to report back to you this week about my 2003 X2 and its "hot starting problem" but the dealer can not replicate the problem! He said he ran it for over an hour and a half on three separate occasions to be sure it was hot enough and our boat started like a dream every time. This is a strange phenomenon since we experienced the "hot-start problem" two days in a row. Anyway... I'll let you know if we learn anything new later on.

Where are you in your investigations?

08-05-2006, 09:42 AM
I have the same problem on my boat. Where is the IAC located?


08-05-2006, 10:22 AM
The IAC is located at the front right of the throttle body and has a four wire plug (green/white, green/black, blue/white, blue/black). TBI is a bit easier to get to but the difference is in how the throttle bodies are oriented.

What makes you think it's the IAC that's causing your problem? If you think you need to clean the pintle, don't use carb cleaner- some of them can damage the plastic.

08-05-2006, 10:24 AM
jdjob- if the dealer didn't run it on the water, it's really not a valid test. They need to run it the same way you did and under similar loads. Running it on a trailer is hardly the same.

08-05-2006, 08:56 PM
Wow, I didn't know so many people were having the same problems that I am.

I had the exact same hot starting issues as Jesse and Eric above. It happened once when I began this thread, but I tried everything I could think of to get the problem to occur again and it would just start and run beautifully every time. We even went wakeboarding about 4 or 5 more times (4+ hours each time) with no failure.

Well it finally failed to start again and this morning and luckily I was prepared with my fuel pressure gauge and DMM. We were still on the ramp when it failed to start so I was spared the embarassment of being towed. I hooked the fuel pressure gauge up and bingo! 0 psi. Key off, key on, cranking, nothing, always 0 psi. I pulled the wiring connecter off of the pump and checked with my DMM and got a solid +12v from the grey to the black wires when the key was turned on. So this suggested what we all have been dreading, the $500+ fuel pump that Mastercraft supposedly has backorderd.

Luckily some of the guys in the below thread had a part number of the pump only which is a common AC Delco electric fuel pump.


For all you do-it-yourselfers out there, the replacement isn't really that difficult. I cross referenced the AC Delco part number EP3156 and my local Advance Auto parts had the pump for about $68 after tax. The Advance store doesn't carry AC Delco, but they do carry "Master" brand fuel pumps (sounds perfect for a Mastercraft, lol).

If anyone else needs to replace one of these pumps themselves to get back on the water ASAP, ask for Master part number E2065. If your local auto parts store doesn't work by part numbers you can tell them you want a fuel pump for a 1992 Ford Tempo with any engine (I laughed for quite some time when I found out that my $30000+ wakeboard boat uses a fuel pump from a 1992 Ford Tempo). At least they offer a 1 year warranty!!!

I also replaced the fuel line that runs between the pump and the pump housing because it looked a little questionable after I removed the old pump. The new 1/4" I.D. nylon line and pair of fuel injector hose clamps ran me a grand total of $4.

If you do attempt this yourself, I would suggest doing so in an area well away from your house with an extinguisher closeby since you will be dealing with raw fuel. You will make quite a mess when you pull the pump. It isn't necessary to remove the fuel lines from the pump since they can simply be removed with open end wrenches up at the throttle body.

She runs well again now, and holds a steady 29-30 psi fuel pressure with the new pump which is much, much quieter than the old pump. Hope this helps everyone else out there with the same problem.


08-07-2006, 04:31 PM
Thank you so much everyone! I feel much better informed about this whole issue than my dealer! Hmmm... perhaps that indicates a problem. (-:

05-12-2007, 11:50 PM
Man this thread was great. I had the same problem, replaced the pump in the housing it took a total of one hour and cost all of 69 dollars...

05-14-2007, 10:18 AM
Thanks for bringing this back to the top! The guys who used the auto fuel pump - still working with no additional problems??

05-15-2007, 11:23 AM
Just tried it out last night while skiing, worked with no problem. I will post in a week or two to let you know how it is going....

07-09-2007, 01:38 PM
Bump for reference