PDA

View Full Version : 1994 MC205 wiring mess and no fuel to TBI


delbert
07-18-2012, 10:42 PM
Help please....Bought a boat that had a new rebuilt engine (1994 Indmar 350 TBI) and the wiring harness was a mess. Plugged everything back in and the engine turns over but I am not getting fuel to the throttle body. I poured a little gas in manually and it would kick and sputter.

Had the local dealer look at it and they checked the throttle body and it worked when power was fed directly from the battery. They also checked the engine with a test ECM and still no fuel. They indicated that I need a new wiring harness but nobody has one. Going back to pick up the boat and it is still not running. Any steps on things to test to help pinpoint my problem.

Appreciate the help.
Brian

ahhudgins
07-19-2012, 07:00 PM
Help please....Bought a boat that had a new rebuilt engine (1994 Indmar 350 TBI) and the wiring harness was a mess. Plugged everything back in and the engine turns over but I am not getting fuel to the throttle body. I poured a little gas in manually and it would kick and sputter.

Had the local dealer look at it and they checked the throttle body and it worked when power was fed directly from the battery. They also checked the engine with a test ECM and still no fuel. They indicated that I need a new wiring harness but nobody has one. Going back to pick up the boat and it is still not running. Any steps on things to test to help pinpoint my problem.

Appreciate the help.
Brian

I have no idea what that means...what did they power up with the battery?? The injectors in the TBI are PWM (pulse width modulated) so I'm guessing that they put power directly on the fuel pump? Did the engine actually run when they did their so called "test". First two things I would want to know is: #1 Does the fuel pump come on for a few seconds (should hear a slight buzzing noise) when you turn the key to the RUN position without cranking the engine. #2 Do you have spark at the plugs when it's cranking.

JimN
07-19-2012, 07:10 PM
Help please....Bought a boat that had a new rebuilt engine (1994 Indmar 350 TBI) and the wiring harness was a mess. Plugged everything back in and the engine turns over but I am not getting fuel to the throttle body. I poured a little gas in manually and it would kick and sputter.

Had the local dealer look at it and they checked the throttle body and it worked when power was fed directly from the battery. They also checked the engine with a test ECM and still no fuel. They indicated that I need a new wiring harness but nobody has one. Going back to pick up the boat and it is still not running. Any steps on things to test to help pinpoint my problem.

Appreciate the help.
Brian

Photos- we need lots of photos. (Why do I feel like John Belushi in 'The Blues Brothers', at the classy restaurant?)

Was the engine harness cut open, or does it look like it's all original. If it's original, it's very neat and has black split wire loom, covered with electrical tape.

Look for any loose ground wires that should be attached at the rear of the engine. Pull the loom open where the ground wires come out- one may have broken off and if it's the one for the fuel pump, it won't work.

When you turn the key to on but don't crank, do you hear a buzzing sound for about 3 seconds? You should. If you don't, listen for a click at the engine- that should be from one of the three relays. Check all of the fuses at the ECM- this is where the relays should be located, too.

This should last you a while- if you don't have a multi-meter, get one and learn how to use it. You'll need to check/verify voltages and resistance in several places.

Where are you located?

delbert
07-20-2012, 12:05 AM
I will take pictures and post soon but still have to pick the boat up from the dealer. Hopefully the information below will help clarify some information for now.

1. The fuel pump does cycle or buzz for a couple seconds when the key is turned on.
2. Since it kicked when I manually poured some gas in the TBI I believe spark is fine. Since it looks like a fuel issue I started with that.
3. The dealer somehow tested the TBI by providing power to the injectors and they did spray.
4. When I got the boat the wires were all tangled up and only half hooked up to the rebuilt engine. I plugged in all the remaining connections to the matching connectors. Seemed straight forward but not sure everything is correct. It is definitely not a clean well organized wiring harness right now. Will look to unplug and untangle everything as well.

Thanks
Brian

JimN
07-20-2012, 07:58 AM
I will take pictures and post soon but still have to pick the boat up from the dealer. Hopefully the information below will help clarify some information for now.

1. The fuel pump does cycle or buzz for a couple seconds when the key is turned on.
2. Since it kicked when I manually poured some gas in the TBI I believe spark is fine. Since it looks like a fuel issue I started with that.
3. The dealer somehow tested the TBI by providing power to the injectors and they did spray.
4. When I got the boat the wires were all tangled up and only half hooked up to the rebuilt engine. I plugged in all the remaining connections to the matching connectors. Seemed straight forward but not sure everything is correct. It is definitely not a clean well organized wiring harness right now. Will look to unplug and untangle everything as well.

Thanks
Brian

Who butchered the harness- previous owner? Yikes!

OK, I would say the fuel pump ground and relay grounds might be OK. There aren't many things that would keep the engine from providing fuel. Just for grins, unplug the harness from the TPS (Throttle Position Sensor)- it's on the throttle body, where the throttle plate pivots. If you have a TPS from an LT-1, cranking with the throttle in the normal position that will allow only idle speed once it starts will keep the ECM from delivering fuel because, to the ECM, it looks like it's at WOT. Cranking at WOT is how you would clear a flooded engine with fuel injection. You could also open the throttle a bit to check this- don't increase the throttle position much, though.

If you have a timing light, use it to verify when you have spark- it should light up any tine you crank it with the lanyard in place. Your gauges move when you turn the key to ON, right? What about when you crank- do you still see the gauges working? You shouldn't- the ignition key's bypass position should only send current to certain areas during cranking. Make sure the thinner red wire is in the right place on the starter solenoid, too. If that's not, you won't have current going to the ignition leads to the ECM and that will keep it from delivering fuel.

Thrall
07-20-2012, 10:36 AM
I've posted some engine troubleshooting docs form an Indmar manual on here a couple times. Maybe you can find them. Search LT-1 or something. The docs are for the TBI engines as well, mid 90's. I don;t have them handy to re-post.
So you have power to the fuel pump as needed, but not the injectors, it sounds. I'd start at teh injectors and trace back the wires from there to the ECM. If a ECM swap didn't do it then there may be a break in the injector wires somewhere.

André
07-20-2012, 10:47 AM
On the dash,there's also a breaker reset push button called "Injection".Try to push it and see if you feel a click when pressing it.
Pretty sure you already did this but...

ahhudgins
07-20-2012, 10:55 AM
I will take pictures and post soon but still have to pick the boat up from the dealer. Hopefully the information below will help clarify some information for now.

1. The fuel pump does cycle or buzz for a couple seconds when the key is turned on.
2. Since it kicked when I manually poured some gas in the TBI I believe spark is fine. Since it looks like a fuel issue I started with that.
3. The dealer somehow tested the TBI by providing power to the injectors and they did spray.
4. When I got the boat the wires were all tangled up and only half hooked up to the rebuilt engine. I plugged in all the remaining connections to the matching connectors. Seemed straight forward but not sure everything is correct. It is definitely not a clean well organized wiring harness right now. Will look to unplug and untangle everything as well.

Thanks
Brian

My 95 doesn't have a schrader valve to check for fuel pressure, does your 94?
Jim, I'm asking this for my own knowledge as well. When the ignition key is turned to the "ON" position and the fuel pump comes on, is it a set time that the pump runs or does it stop once the pressure builds? This may indicate that he has fuel pressure since the dealership could fire the injectors. Don't know if they by-passed the ECM to run the fuel pump either.

Doesn't the ECM look for the signal from the distributor before it fires the injectors?
Sounds like a wiring nightmare.

JimN
07-20-2012, 11:38 AM
My 95 doesn't have a schrader valve to check for fuel pressure, does your 94?
Jim, I'm asking this for my own knowledge as well. When the ignition key is turned to the "ON" position and the fuel pump comes on, is it a set time that the pump runs or does it stop once the pressure builds? This may indicate that he has fuel pressure since the dealership could fire the injectors. Don't know if they by-passed the ECM to run the fuel pump either.

Doesn't the ECM look for the signal from the distributor before it fires the injectors?
Sounds like a wiring nightmare.

3 seconds, to prime the fuel line and pump. To bypass the ECM, a jumper needs to be connected to the relay trigger terminal for the fuel pump, but it would be best to remove the relay for this- don't want to back-feed current to the ECM. If someone did without removing the relay or blocking the current, it's not a good thing but the fact that the test ECM was used may indicate that the ECM isn't at fault. OTOH, it's necessary to find out if the test ECM still works normally. To test fire the injectors, 12VDC needs to be connected to the + lead on the injector and - on the other. This can be done with/without the plug being removed. but again, it's best to eliminate any chance of back-feeding current.

I would recommend testing for continuity from the injectors to the ECM, from all relays to the appropriate end and for voltage at all three relays. Also, the fuses may look OK, but be blown. Check for voltage on both sides of the fuse while they're in the fuse holders, preferably at the terminals on the bottom. If you see no voltage on the side past the fuse, check the fuse.

JimN
07-20-2012, 11:43 AM
If someone needs to test fuel pressure, you can get the parts from most hardware and auto parts stores.

The way I would do it if I didn't have the pressure test block is to buy a fuel filter and have a Shrader valve silver-soldered or brazed onto it. Then, the normal filter could be removed and replaced with the test filter for diagnostics. This would obviously be done by removing the filter on the engine and is only necessary for the models without a valve in the fuel line. The other way is to remove the hard fuel line and have a Shrader valve installed on it.

delbert
07-23-2012, 10:49 PM
Picked up the boat Friday and finally had a chance to look at it this evening for a few minutes.

I unhooked the TPS plug and the TBI did spray fuel. Motor would turn over and spray while the TPS was unplugged. When I plugged the TPS back in it would no longer spray.

Should the boat have started since the TBI was spraying fuel? Will likely need to look at timing or spark plug wire order as it only acted like it was going to catch once. Battery was week so will try to assist with a jumper box next time as well.

Thanks again for the help.

delbert
07-24-2012, 08:27 AM
One more thing. Do I need a new TPS sensor or is this a potential wiring issue? Any way to test to make sure which one is the problem?


As you can tell from the pictures I will need to straighten out the wiring mess.

Double D
07-24-2012, 08:31 AM
One more thing. Do I need a new TPS sensor or is this a potential wiring issue? Any way to test to make sure which one is the problem?


As you can tell from the pictures I will need to straighten out the wiring mess.

UGH!!!!!!

JimN
07-24-2012, 09:22 AM
Picked up the boat Friday and finally had a chance to look at it this evening for a few minutes.

I unhooked the TPS plug and the TBI did spray fuel. Motor would turn over and spray while the TPS was unplugged. When I plugged the TPS back in it would no longer spray.

Should the boat have started since the TBI was spraying fuel? Will likely need to look at timing or spark plug wire order as it only acted like it was going to catch once. Battery was week so will try to assist with a jumper box next time as well.

Thanks again for the help.

If you had spark when you drizzled gas into the throttle body, it should start with the TPS harness unplugged. Make sure the safety switch is working properly (make sure the gauges move when you turn the key, especially the voltmeter). If they move and you don't have spark, measure for voltage on the purple wire in the harness at the distributor. If you don't have voltage there, it's not going to start.

To check and change timing, you need to put the ECM in 'Diagnostic Mode'- do a search here for the procedure. The firing order should be on the intake manifold.

ahhudgins
07-24-2012, 12:22 PM
UGH!!!!!!

That's what I call the "Hair net effect". UGH X2!!!!

JimN
07-24-2012, 02:22 PM
One more thing. Do I need a new TPS sensor or is this a potential wiring issue? Any way to test to make sure which one is the problem?


As you can tell from the pictures I will need to straighten out the wiring mess.

Who the frack did that? How many of the wires have been spliced, do they have different colors and gauge between the splices and is it that way throughout the harness? If so, it's going to waste a lot of time trying to figure out where the wires need to go, what's effed up and repair anything that needs it. I think I would start looking for a salvage boat of the same model/year/engine and replace the whole thing. It will be a lot cheaper than having one made or paying someone to weed their way through that one. Plus, it would be reliable- I don't think I would ever trust that one.

delbert
07-24-2012, 07:12 PM
Would love to have a new/used wiring harness but no luck finding one so far. Dealer was looking as well and Indmar no longer makes one. For now I will set timing and see if this one will run as is. Then will untangle the mess and see what I have. Maybe once it is untangled it will not be that bad (splices or cross wiring).

Thanks again for the help.
Brian

JimN
07-24-2012, 07:20 PM
Would love to have a new/used wiring harness but no luck finding one so far. Dealer was looking as well and Indmar no longer makes one. For now I will set timing and see if this one will run as is. Then will untangle the mess and see what I have. Maybe once it is untangled it will not be that bad (splices or cross wiring).

Thanks again for the help.
Brian

Another thing that will indicate whether it was hacked, or just opened- if the spices are twisted and taped, butt spliced or both, it was done by someone who was trying to "work" on it. Any factory splices would have been soldered and heat shrink tubing used.

Call Indmar or MC to see if they have any old harnesses. They were all the same when originally made because they used jigs for making them.

delbert
07-24-2012, 10:22 PM
Worked on the boat a bit this evening. After getting everything set up I messed with the distributor position a bit and then tried to start the engine. TPS was unhooked so TBI was spraying in an alternating pattern. One injector would spray for a second pause and then the other injector would spray for a second then repeat. Engine would kick and act like it wanted to run but just didn't seem to get enough fuel to keep running. Of course since the TPS was not plugged in it would not increase fuel with throttle movement.

Do I need to buy a new TPS or is there a way to test voltage to the TPS before I change it out? Any other recommendations on next steps?

Will reach out to Indmar and Mastercraft to see what I can find out on wiring harness.

JimN
07-24-2012, 10:45 PM
Worked on the boat a bit this evening. After getting everything set up I messed with the distributor position a bit and then tried to start the engine. TPS was unhooked so TBI was spraying in an alternating pattern. One injector would spray for a second pause and then the other injector would spray for a second then repeat. Engine would kick and act like it wanted to run but just didn't seem to get enough fuel to keep running. Of course since the TPS was not plugged in it would not increase fuel with throttle movement.

Do I need to buy a new TPS or is there a way to test voltage to the TPS before I change it out? Any other recommendations on next steps?

Will reach out to Indmar and Mastercraft to see what I can find out on wiring harness.

It should still start if the TPS is unplugged. You can check the wiring- the black is ground and IIRC, it shares the ground with the MAP sensor so if you follow the wires in the harness, you should see where they join. I think it has a gray wire that supplies reference voltage and the green will be the return to the ECM. If the reference voltage is below 5VDC, something is wrong. The MAP sensor uses a 5VDC reference voltage, too.

If your timing is way off, it won't want to run. You can put the timing mark at TDC (with a timing light that has an advance dial) or at 10°BTDC (with no advance dial), connect the timing light to #1 plug wire, turn the key ON and, without cranking, you would rotate the distributor back and forth. You'll see the timing light flash when the lobe causes the pickup coil and IC (Ignition Control) module to induce spark. Snug the hold-down and verify that it didn't move, reset to 10° if necessary and tighten the hold-down. Then, crank it and see if it runs but lube the impeller (or remove it) since you don't need to run it for more than a few seconds.

While you're setting the timing, if you're going to crank it, remove the fuel pump fuse, so you don't dump a lot of gas into the intake and exhaust system, as well as keeping it from going into the crankcase. Letting gas into the crankcase dilutes the oil and that's really bad for its lubricity.

If you get it to run and the fuel delivered is inadequate, measure the resistance of the ECT (Engine Coolant Temperature) sensor. If it's lower than what's in the resistance chart that has been posted here about 100 times and may be a sticky, this will make the ECM think the temperature is very high, which reduces the amount of fuel to the intake. If the engine was actually running and the fuel was alternating, that's another indication that the ECT or the wiring for it has a problem. Alternating form one injector is called 'toggling' and is what happens during RPM reduction, which the car guys call 'Limp Home Mode". Boats don't have a 'Limp Home Mode' because they don't have a radiator to store coolant. If it ever does this when you're on the water, shut it down immediately and let it cool down before you run it again. DO NOT think it will live long if you idle back or run it hard. Either will kill and engine and you should also keep a spare impeller & gasket in the boat at all times. If you haven't seen it in these threads before, I'll make the recommendation that reduces the risk of overheat best- check and clean out the oil cooler frequently. The old manual mentioned this at the front- it said that the oil cooler should be checked and cleared out before running the engine EVERY TIME. You won't see when something goes into it and you can't possibly react fast enough to avoid it.

BTW- if the TPS is unplugged, the ECM defaults to 12% Throttle Position. It will still start and run, but acceleration will be somewhat sluggish.

delbert
07-26-2012, 11:46 PM
Thanks again for the help. Unfortunately not going to get to look at my boat again for another week (or so). Will pick it back up then and continue testing the items mentioned above.

One piece of good new is that I plan to get a few pulls behind my brothers MC.

Brian

delbert
08-07-2012, 10:16 PM
1. Correction/Clarification...When unplugging the wires to the sensor that is inline with throttle plates (TPS) the injectors do not fire or provide fuel to the engine. When I unplug the wire connection on the TB that is more toward the back of the TB (IAC???) the injectors will fire on their alternating pattern as mentioned before.

2. Spent some time untangling the wiring and it looks like it was only tangled. Other than one exception the wiring connections seem to be soldered and shrinked. I believe the wiring harness was not butchered just tangled up. Now I need to get some wire loom to make it look better.

JimN
08-08-2012, 06:58 AM
1. Correction/Clarification...When unplugging the wires to the sensor that is inline with throttle plates (TPS) the injectors do not fire or provide fuel to the engine. When I unplug the wire connection on the TB that is more toward the back of the TB (IAC???) the injectors will fire on their alternating pattern as mentioned before.

2. Spent some time untangling the wiring and it looks like it was only tangled. Other than one exception the wiring connections seem to be soldered and shrinked. I believe the wiring harness was not butchered just tangled up. Now I need to get some wire loom to make it look better.

It SHOULD deliver fuel when the TPS harness is unplugged and unplugging the IAC harness (four wires- two blue and two green) shouldn't cause it to alternate the injectors. Something has been changed. What are the colors of the wires in the TPS harness?

delbert
08-08-2012, 01:14 PM
TPS has three wires (white, black, and blue)

IAC has four wires (purple/white, white, black/red, and white/black)

delbert
08-08-2012, 01:32 PM
JimN, You are fabulous!!! Ran home to pick up some tools and did a quick look at the boat. I saw that there were the green and blue wires with the same connector that were plugged into the back of the distributor. Switched the 2 plugs and she fired right up. Only ran for a couple seconds since I did not have water hooked up. Will check out this evening to make sure everything else is working. Looks like I may be at the lake this weekend.

Big thanks again.
Brian

JimN
08-08-2012, 06:31 PM
TPS has three wires (white, black, and blue)

IAC has four wires (purple/white, white, black/red, and white/black)

As soon as I saw the colors of the wires in the IAC, I was just about to tell you to look at the distributor for the IAC harness but you beat me to it.

JimN
08-08-2012, 06:32 PM
JimN, You are fabulous!!! Ran home to pick up some tools and did a quick look at the boat. I saw that there were the green and blue wires with the same connector that were plugged into the back of the distributor. Switched the 2 plugs and she fired right up. Only ran for a couple seconds since I did not have water hooked up. Will check out this evening to make sure everything else is working. Looks like I may be at the lake this weekend.

Big thanks again.
Brian

Don't EVER call me 'fabulous!:D