Help, 2001 5.0efi died and wont start...

[wakeboardbob]

elp, 2001 5.0efi died and wont start. This is my situation. Boat ran fine last wed, sat fueled up for camping trip, went to ramp and boat was hard to start...5 minutes or so. Boat always starts on second crank. Boat stalled a couple times getting to island but just thought it was a fluke. Let it sit for an hour and it started but stalled right away. Friend shows up, takes me back to get fuel filter and plugs, install them and it fired right up and seems to idle after a bit of grumbling. Old plugs needed to be changed anyway BUT they were wet/fouled. Pulled off island and got about 200 yards when she stalls. Start it back up but it wont go in gear without stalling then it wont even start. It gets spark and i see fuel spraying in the TB. I tested the throttle position sensor with the 9volt battery and moved it through its range, seemed fine. I tested the map sensor with a vacuum gauge and 9volt battery, seemed like it had a linear output...not sure what output corelates to what in hg? Just changed dist cap and rotor, still same. I am contemplating new plugs again but wanted some profession help from the forum...oh yea Im new to Iboats, my name is Bob and I have an addiction...900+ hours

 

[Glastron_V210]

Re: Help, 2001 5.0efi died and wont start...

When you say plugs were wet, do you mean fuel or water??

Anyway, my suspicion is fuel pump. Buy a guage and check that the fuel pressure is within spec.

With EFI this is critical and so easy to check. Can you hear your fuel pump prime when you go to the run position?

That's where I'd start.

Chay

 

[Glastron_V210]

Re: Help, 2001 5.0efi died and wont start...

BTW, the map and tps etc are typically GM 5 volt devices...they probably will be ok with 9v, but next time use a lower voltage source.

C

 

[wakeboardbob]

Re: Help, 2001 5.0efi died and wont start...

Yes i do hear the fuel pump prime and see a strong steady stream of fuel when cranking.
Update, tested the voltage at the map connector and it is 5v dc. I pulled the plugs, cleaned them and tried to start again. It made No signs of any cylinder wanting to fire or backfire...oh yea when the problem started it was occasionally backfiring thru the throttle body. I did recheck and the coil is sending strong spark to the distrubutor cap. Might do a quick compression test and make sure everything is ok down below.

 

[wakeboardbob]

Re: Help, 2001 5.0efi died and wont start...

Back to the top of the pile...

 

[Don S]

Re: Help, 2001 5.0efi died and wont start...

Not sure why you are messing with the TPS and MAP sensors. They won't keep it from starting.
Have you checked to see if you have spark? Have you checked your fuel filter water seperator to see if there was water in it. Since the problem started after refueling, I would sure be looking.

Also head up to the Adults Only sticky at the top of this forum and download a service manual and stop testing things your way.

 

[wakeboardbob]

Re: Help, 2001 5.0efi died and wont start...

Thanks for replying Don. I was trying to follow a proper troubleshooting guide but may be creating more problems, IE:because of initial problem fouling plugs, now it doesnt start? I just bought new plugs and earlier took some voltage readings at the 3 small fuses next to the ecm/ecu(top of the motor). Voltage was dipping to the 10's when cranking. I went through and cleaned some battery cable connections at the block and battery as well as pulled the main harness from the motor with the 10 or so pins and spread them out a bit, they were clean, and reconnected. I have read that the efi boats are sensitive to low voltage but since I saw, what looked to be, strong spark I didnt realy think it could be the problem. I have since bought some starting fluid and tried to crank with the throttle in the flood position, 50-75%, and just tried to spray the starting fluid but did not have any luck. I will install the new plugs after trying to clear out the cyclinders of any excess fuel. I do appreciate anyones ideas and I do have the manual and might just start my troubleshooting from scratch so I dont miss anything simple.

 

[wakeboardbob]

Re: Help, 2001 5.0efi died and wont start...

Found the problem. Evidently my idea of what a spark is supposed to be and the coils were different. Purchased an $8 spark gap tester from autozone, even though you could clearly see a spark when turning motor over. Tested coil connected to wire harness-bad, ran a hot straight from the battery to the + on the coil and rapidly touched the negative to the ground on the battery, completely eliminating any possible corrosion on the harness-still bad? Well the spark gap tester must be bad cause I have it screwed way down. Try it on sons car and hell yes it works. I knew it wasnt bad connections on the coils as I had cleaned and retightened. Install new coil and tested with spark gap checker is that what a spark is supposed to look like. I guess all these years being spoiled with crap I dont have to work on has softened my skills. With 900+ hours I gues some stuff is going to break eventually. Now about that cylinder that was a bit low on the starboard side...