1994 MC205 wiring mess and no fuel to TBI

[delbert]

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]

Originally Posted by delbert

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]

Originally Posted by delbert

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]

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]

Originally Posted by delbert

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]

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]

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]

Originally Posted by delbert

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]

Originally Posted by ahhudgins

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]

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.