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View Full Version : 94 190, rpm issue


bret
08-02-2010, 11:17 PM
Hey gents, for the first time in 16 years I have my first little issue. Skied this morning, and this afternoon, taking the boat back to the marina, I gave it a full throttle run and the boat bogged after about 3800 rpm. ***? Got the boat back, plugged in the code mate, flashed 12, and nothing else - ok. check the valve on the hose from the fuel tank, maybe just a bit from WO, so opened it fully, took it back out, same issue but boat is Perfect to 3/4 throttle, perfect. So, plug wires, 3 years old, I did go out and buy new plugs this afternoon but they didn't have the fuel filter, will get it in the a.m. I thought, thought that I heard the fuel pump a bit more than normal.

If anyone has had this issue, would appreciate some input before going to replace parts and chase it, especially with a $290 fuel pump. Boat starts and idles fine, timing was checked a month or so ago, spot on, and no code mate faults. TPS? Fuel pump...has anyone really had their screen pick up get dirty and slow fuel delivery? I was down pretty low and then got 1/2 tank today and today I have issues for the first time in 16 years. I don't think it's the fuel, could be but boat runs too well in the below 3600 rpm range. TIA

east tx skier
08-02-2010, 11:32 PM
Looks like you got your login issues fixed. I'll repeat the high points of my pm

Flame arrestor, clean?

Perfect Pass servo motor, tensioning?

Can you even adjust the timing on the LT1?

Did you get some fishing line wrapped around your prop?

bret
08-02-2010, 11:44 PM
yes, first thing I checked

not equipped

standard 275 motor, tweaked by Mr Tehan(manifold, TB, and ecu)

don't think so..but didn't check LOL

I'll start with the plugs, cap/rotor, and fuel filter in the morning.

east tx skier
08-03-2010, 12:22 AM
yes, first thing I checked

not equipped

standard 275 motor, tweaked by Mr Tehan(manifold, TB, and ecu)

don't think so..but didn't check LOL

I'll start with the plugs, cap/rotor, and fuel filter in the morning.

How about your injectors?

André
08-03-2010, 09:32 AM
Classic case of clugged screen under the brass fitting of the inlet of the fuel pump.
Remove fitting,clean and reassemble.

JimN
08-03-2010, 09:37 AM
The first thing to test is guessing is fuel pressure. ALWAYS. If this isn't done, guessing is the only way the cause will be found. Once htis is done, check the screen.

André
08-03-2010, 09:44 AM
The first thing to test is guessing is fuel pressure. ALWAYS. If this isn't done, guessing is the only way the cause will be found. Once htis is done, check the screen.

There's no place to install a gauge on those old TBI.You would have to splice the supply line to install a gauge.
Or is there somewhere else you can install it?:confused:

JimN
08-03-2010, 11:05 AM
There's no place to install a gauge on those old TBI.You would have to splice the supply line to install a gauge.
Or is there somewhere else you can install it?:confused:

There's no place from the factory but if someone were to go to a good parts store, a piece of the same kind of fuel line, a T block and a few compression fittings could be used to build one.

Hey- look at what I found! Here's a link- it's not cheap but it's made for this purpose.

http://www.toolmarket.com/product-gm-tbi-fuel-pressure-adapter_3265.aspx?cid=567

It's made by OTC and sold by many dealers. The local price I got was $67.95.

bret
08-03-2010, 11:45 AM
Love that tool, it will be in the box soon. Plugs were fouled. A couple of months ago (I've been traveling for 6 weeks straight) my distributor got loose from the retainer bolt coming loose, not sure how but the boat got out of time and that's probably when they fouled - I reset the timing, torqued down the bolt, and the boat ran fine until I did some full throttle runs yesterday. My son wakeboards at 17-18, slaloms at 28, and I ski at 32 mph. Changed plugs this morning, fuel filter too, and she bumped out at 4300-4400 rpm; I have the 3 blade on at the moment.

Thanks for the tool link Jim!!

east tx skier
08-03-2010, 11:51 AM
You should have sold me that boat, Bret. ;)

JimN
08-03-2010, 03:10 PM
Love that tool, it will be in the box soon. Plugs were fouled. A couple of months ago (I've been traveling for 6 weeks straight) my distributor got loose from the retainer bolt coming loose, not sure how but the boat got out of time and that's probably when they fouled - I reset the timing, torqued down the bolt, and the boat ran fine until I did some full throttle runs yesterday. My son wakeboards at 17-18, slaloms at 28, and I ski at 32 mph. Changed plugs this morning, fuel filter too, and she bumped out at 4300-4400 rpm; I have the 3 blade on at the moment.

Thanks for the tool link Jim!!

I had never seen that tool before, either. I have one that works with a flexible line and connects directly to the throttle body but the one that displaces the filter is better for most people including me, if I want to test the pressure on my truck.

bret
08-25-2010, 11:43 AM
Andre wins. The INNER screen on the fuel pump had $hite in there. The screen, you have to take off the barb hose fitting AND the NPT to JIC nipple to get to the screen. The boat did it a couple of days later, actually, it could have been this way for a bit, as I'm not one to run the you know what out of the boat and when I would give it full throttle it was usually early in the morning when the lake was like a sheet of glass.

So, when this 3/4 tank gets to below 1/4, gas tank is coming out for a good cleaning and clean the pick up. The gas tank was last pulled about 10 years ago so guess it's time. It's not that hard just a PITA to get to the little hardware.

JimN
08-25-2010, 02:36 PM
Andre wins. The INNER screen on the fuel pump had $hite in there. The screen, you have to take off the barb hose fitting AND the NPT to JIC nipple to get to the screen. The boat did it a couple of days later, actually, it could have been this way for a bit, as I'm not one to run the you know what out of the boat and when I would give it full throttle it was usually early in the morning when the lake was like a sheet of glass.

So, when this 3/4 tank gets to below 1/4, gas tank is coming out for a good cleaning and clean the pick up. The gas tank was last pulled about 10 years ago so guess it's time. It's not that hard just a PITA to get to the little hardware.

When anyone mentions the screen on the pump, that's the one we're referring to. It's the first line of defense when the only filter is after the pump and usually causes a drop in RPM at about 2K-3K when under load..

DooSPX
08-25-2010, 05:00 PM
bret its great to see you on here again!

92 190 PS
08-25-2010, 05:35 PM
Andre wins. The INNER screen on the fuel pump had $hite in there. The screen, you have to take off the barb hose fitting AND the NPT to JIC nipple to get to the screen. The boat did it a couple of days later, actually, it could have been this way for a bit, as I'm not one to run the you know what out of the boat and when I would give it full throttle it was usually early in the morning when the lake was like a sheet of glass.

So, when this 3/4 tank gets to below 1/4, gas tank is coming out for a good cleaning and clean the pick up. The gas tank was last pulled about 10 years ago so guess it's time. It's not that hard just a PITA to get to the little hardware.


Classic. Same thing happened a while back on a friends CC and I removed the screen and a couple little pieces of crap in there (after reading a similar thread to this). Fired it up and it ran like a champ. He looked at me like I was nuts and then thanked me and gave me a beer. He asked how the hell I knew to look at the screen and I told him he needed to find his way to this board and next time he bought a boat to buy a Mastercraft...:)

chico
08-25-2010, 07:56 PM
I put another filter at the fuel tank on my 94.

André
08-25-2010, 08:05 PM
Andre wins...

Great!!!
I never owned a Porsche before...:)

bret
08-27-2010, 06:30 PM
So here goes my day for the fuel tank:

7:00 Boat on the trailer, headed home (7 minutes from the marina)
8:00 oil is drained, filter and new oil in.
8:15 start getting engine box off, rear floor plate and back carpet, I want all access
9:00 I attach a hose and barb to the hose on the bottom of the fuel pump and let the gas drain all it will into the two 5 gallon cans under the boat. Get a few gallons, about it. Time to pull it.
Get the hold downs off, 4 ea, move battery over, slide tank a few inches and ease it out. Disconnect level sensor, disconnect pick up, return and vent lines, then disassemble the fuel neck.
10:15 It's out and my neighbors get free gas for their lawnmowers
Tank is not that bad but there is crap in the bottom. The bafle chamber is pretty clean and the bottom of the pickup screen is suprisingly CLEAN.
Clean out as far as I can reach, rig up a rag on some extension to get the far end - ok, done.
Put it all back together, tank probably weighs 20# empty.
11:45 tank back in and the fittings are on and hose clamps tight. Don't forget your ground, which is a wire that attaches to one of the bolts on the filler neck top housing. Turkey wrap, Bud Light(1) and a big of glass of ice water.
12:55 done. Engine box back on, rudder, steering cable and steering knuckle all greased while access was there. Get my pump and change trans fluid too.
1:10 wipe the boat down, get the cleaner/polish/wax ready.
3:20 head to Exxon, 93 octane for 1/2 tank
3:40 in the water, and fires up first try. You CAN put in too MUCH Chevron Techron - I added some before all this over the past couple of days and the boat was smoking just a bit at idle - not a fan of SeaFoam. Anyway, boat ran GREAT. I have the 4 blade on and she hit 43 mph. Back at the marina, idle smooth, no smoke, not even an exhaust line on the back of the boat when I lifted it out!

I'm scabbing off the Marinas WiFi, I would have run it longer but it was just to windy.

I've tried thinking what caused this since I didn't find total $hite in the bottom. This was the first year that I did not change fuel filters on my spring start up. I have been really busy at work with us out at the Horizon site, and working on the race car trying to get it ready for October.

Thanks for the tips gents, here's to late fall boating - we're skiing at 7 in the morning.

bret
07-17-2013, 08:05 AM
Just wanted to bring this back to life in case others get the same RPM drop - this happened the other day at the course. I had just put in Perfect Pass so I was like did the servo motor or RPM wiring do this? Swapped out the ball jt back to regular cable and same thing, then I knew it was the fuel pump screen. So, 8 years and 11 months from the last time. In line filter going in this weekend for a bit of added protection.

André
07-17-2013, 11:44 AM
... then I knew it was the fuel pump screen. So, 8 years and 11 months from the last time...
9 years already.Just seems like yesterday.:)
With 4 dogs,i have to do mine every 3 years!
Never understood having the filter after the pump...Just back from the course and the old 94 pullled 6 great sets again this morning including my first 32 off this season(Ya...i know ,sad).
One of the guy who travel a lot,ski all the big ski school in the south and ski often a CC 200 was amaze by the nice wake of our old 94 MC!!!