No hot start 5.0 GXI

[Leardriver]

I'm helping work on a boat with a weird hot start problem.
'05 5.0 GXI-E, PN 3869255, SN 4012145906 with a SX-M drive.

The boat starts cold perfectly, idles like a Lexus, makes great power, and operates flawlessly. It continues to run perfectly when it's warm, but my friend is afraid to shut it off, because...

It won't restart! It turns over great, coughs and catches a little like it wants to run, but won't stay running. It doesn't matter what the throttle position is, how much you pump it ( I know it's FI). It has dual batteries and plenty of juice to crank.

It's frustrating because it idles and runs so flawlessly until you shut it off. When the no-start condition is manifesting itself, both fuel pumps are whirring and activating with the ignition switch when it is turned on. When it cools off overnight, it starts great. It's hard to believe it's a fuel flow problem, even though that's the symptom when it won't start, because once it does start, it runs so well forever until it's shut off. All of these experiences are on the water.

Some kind of sensor? The dealers are busy for weeks to plug it in and check for codes.

Anybody heard of a similar problem?

 

[Don S]

Re: No hot start 5.0 GXI

Has he tried to move the throttle to the WOT (Wide Open Throttle) position? That will clear a flood condition and help determine the direction to go in troubleshooting.
It may also be a vapor lock if things are hot enough in the engine compartment.
Might try opening the engine cover and cooling things down.

 

[Leardriver]

Re: No hot start 5.0 GXI

That makes perfect sense. I did open the engine compartment and spray cold water on all of the lines and let it sit for a half hour, opened the gas cap to check for a plugged vent like we do on dirt bikes.

The throttle has been pumped, but not continually held open. I'll try and report back.

 

[Don S]

Re: No hot start 5.0 GXI

It's fuel injection, pumping the throttle does nothing. Just hold it full open to clear flood.

 

[Leardriver]

Re: No hot start 5.0 GXI

I know, that's why I admitted that it was FI while the throttle was being pumped. Anyway, just tried cranking it for quite a while in the WOT position, and not a hint of starting.

 

[Don S]

Re: No hot start 5.0 GXI

Is the engine hot? Do you have spark?

 

[Leardriver]

Re: No hot start 5.0 GXI

It has plenty of spark. Just tried again, and it wants to run. It will start, run for 3-4 seconds, and quit. Varying throttle position doesn't help.
If I cycle the ignition on and off to run the fuel pump, and then try to start it, it seems to like the additional fuel pump priming and run for a second longer. I could use a fuel pressure gauge.

 

[Don S]

Re: No hot start 5.0 GXI

Time to start checking fuel filters (empty them and see how much crud and water) and do some fuel pressure checks.
If you don't have pressure from the high pressure pump, it's not going to run, and if you don't have fuel being supplied from the low pressure pump, you will not have anything for the high pressure pump to work with.

Here is the OEM manual for the EFI diagnostics you can download. You're going to need it.
http://www.4shared.com/document/cfN9HVF3/7742218_EFI_Diagnostics.html?

 

[Leardriver]

Re: No hot start 5.0 GXI

Awesome! I've been looking online for this manual.

I agree with all of your suggestions. I don't have a gauge to measure fuel pressure, but I'll figure something out.

Thanks for your help.

 

[Leardriver]

Re: No hot start 5.0 GXI

Ok, I got the fuel filter off. and I wish I could say that it was gunked up, but it looked very clean. Here's the weird part-
With the filter off, the engine started and purred. I know there's a little reservoir of fuel in the fuel pumps, apparently enough to run for a few seconds. So, was there some unseen plug in the filter that prevented fuel flow? Unlikely, but maybe.

Did taking the filter off relieve some air blockage or venting problem, and allow previously vapor locked fuel to flow? I don't know either. I'll replace the filter asap and I already verified that the correct part number, 3862228, was installed, and test again.

Thanks Don, for your suggestions. I always like to start with the simplest thing first also, and maybe a bad fuel filter was all it was. Time will tell.