Engine Starts Then Dies

[idiambulance]

When I first got my vehicle if I let it sit for a couple days it wouldnt start. It didnt have any problems when I was running it every day. A friend suggested that it might be my return lines loosing pressure. After looking at them they desperately needed to be replaced. After replacing them I now have a new issue. The vehicle will fire right up and run well for 2-4ish minutes. It will then loose power and rev up doing that cycle a couple times then dies out. If i crack a couple injector lines and bleed the system I can get it started again. I havent been driving it much as im doing some work on it but now its to the point that I had it running yesterday and it died just a few moments ago. Im not sure if its the dash gauges or the sensors but I also have no oil pressure and I suspect my coolant temp sensor might also be faulty. Any help would be greatly appreciated.

 

[Farmer Rock]

Sounds like a drain back issue to me. You have a pinhole or leak somewhere in the fuel system that is causing the fuel to drain back to the tank after sitting. It has just enough fuel in the injection pump to start , but then the air come in and kills it. What are the specs of this vehicle? Is it a truck or van? 6.9 or 7.3?


Rock

 

[idiambulance]

Sounds like a drain back issue to me. You have a pinhole or leak somewhere in the fuel system that is causing the fuel to drain back to the tank after sitting. It has just enough fuel in the injection pump to start , but then the air come in and kills it. What are the specs of this vehicle? Is it a truck or van? 6.9 or 7.3?


Rock

It is a 6.9 ambulance. It has two tanks and the problem exists on both tanks. I recently drained the fuel and found some water in my fuel filter. I tried to open the water fuel seperator but it didnt do anything. Could the problem be there?

 

[Farmer Rock]

The water separators are known to leak causing drain back and or air intrusion,so it's very possible. What you described doesn't sound like water in fuel at all, but to address that, was it only at the filter you saw water? And how much? If it was just a little in the filter I wouldn't worry about it unless it was all rusted from water being in the fuel. Has it been sitting awhile? That won't help the fuel out either if it gets a lot of condensation.
Did you drain it before or after you found the water?


Rock

 

[Big Bart]

Double check your return lines. Sounds like air intrusion to me too.

1) Did you buy a new return line kit with o-rings and caps? Or did you just try replacing the hoses in between? (Always do the kit.) Let us know.
2) Did you lube up the orings with ATF, Diesel, or some o-ring grease? Maybe one pinched or got cut. They are a little tricky but "pop" on when you put them on the injector if done right. Let us know.
3) Open all your injectors lines at the injector. Run the starter for 10 seconds on 20 seconds off. Get all the air out! Then re-tighten and try again. Mabye you still have some air trapped somewhere and you are close to it running.

You already had a air issue so maybe while working you bumped on something and made it worse. So after all this chase backwards to the tank selector valve and from there to the fuel tanks. If both tanks have the same issue, it is likely between the engine and the tank selector valve. (VS both tanks have leaks between the selector valve and tank.)

Still stalling, next replace the fuel filter.(You said you saw water in it, you did not mention replacing it. Perhaps you have. If so make sure it got screwed on tight. Always fill it with ATF or diesel before you put it back on. (More air you don't need to deal with.) Perhaps the fuel seperator or lines to it are causing an issue. Many folks have challenges with these.

Then check your lift pump is working. Hook to the shrader valve on the fuel pump and watch the PSI while running. You should have at around 5 psi. Anyting under 3psi and you likely have a bad/weak lift pump or a blockage to or from it. If you have good PSI you may want to replace the rubber hose from the fuel line to the lift pump. Use new clamps. That will insure you do not have a leak there.

Could be you just had a mishap when doing the return lines. As you said it was running before (Just hard starting after sitting for a while.), now it only runs for a short time after doing the lines and looking at the fuel filter. Could be you still have some air you need to get out of the lines.

After you get it running you can address the dash gauges. The stock dash gauges and sensors are not very good or reliable. Advice from this group is always put in a second set of 3rd party gauges, you then will see the problem before it hurts your engine. Oil pressure, water temp, and voltage. Add EGT and boost if running a turbo.

Let us know what you found.

 

[idiambulance]

The water separators are known to leak causing drain back and or air intrusion,so it's very possible. What you described doesn't sound like water in fuel at all, but to address that, was it only at the filter you saw water? And how much? If it was just a little in the filter I wouldn't worry about it unless it was all rusted from water being in the fuel. Has it been sitting awhile? That won't help the fuel out either if it gets a lot of condensation.
Did you drain it before or after you found the water?


Rock

There was a good amount of water in the fuel filter when I dumped it out. The fuel that was in it was there from the original owner so it had probably been in there for a while as it wasnt registered. Ive had the vehicle since October. Im turning it into a camper so ive been doing service runs but it hasnt gotten many driving miles on it. I drained both tanks and added new fuel with fuel cleaner in it. After I put new fuel in it it ran way better but still has the same problem starting. Since the water fuel seperator isnt working im trying to find a replacement unit that doesnt have the problems these old ones seem to have (based on my forum reading). Sounds like ill be bumping that up on the list of things I need to do. Do you think the leak could be from a hardline or is it more likely from a rubber line?

 

[Big Bart]

Sounds like your 3rd party water seperator is full or bogus. Should have trapped the water before getting to the fuel filter. (Which will also seperate it.) Perhaps for now for testing by-pass the 3rd party fuel seperator. You may find your issue goes away. (Seperator or hoses to it.)

Look at West Marine, fuel water seperators are almost standard on all boats with onboard tanks for obvious reasons. I run a Raycor on my boat (Diesel Yanmar.), well made, and have not had issues.

 

[idiambulance]

Sounds like your 3rd party water seperator is full or bogus. Should have trapped the water before getting to the fuel filter. (Which will also seperate it.) Perhaps for now for testing by-pass the 3rd party fuel seperator. You may find your issue goes away. (Seperator or hoses to it.)

Look at West Marine, fuel water seperators are almost standard on all boats with onboard tanks for obvious reasons. I run a Raycor on my boat (Diesel Yanmar.), well made, and have not had issues.

Sorry for the confusion I currently have the factory installed separator that doesnt seem to be working. I am wanting to install a third party separator as a future upgrade. I saw on another forum as a temporary solution i could add a rubber hose between the two hardlines to connect the line. That does make a ton of sense to use a marine separator.

 

[IDIBRONCO]

Your factory water seperator may have already been bypassed and that would be why nothing happens when you try to drain it.

 

[Fort Ford]

I had a very similar issue and Russ on this site helped me figure out it was the check valve in the lift pump allowing the fuel to drain back. I had enough fuel in the filter/injector lines to start up and run for a bit, and then it sputtered out. Would start back up after cranking enough to get the lines refilled. Replaced the fuel lift pump and it fixed the issue. Although, my rubber line on the fuel pump is pretty shot, so I'm still planning on replacing that for peace of mind. Worth a look, but not sure how to test that besides just replacing the lift pump.

 

[Stu Bailey]

Oil pressure, water temp, and voltage. Add EGT and boost if running a turbo.

Let us know what you found.

Don’t want to hijack this post but have to ask, is an EGT gauge a thing if you don’t have a turbo? Is that dumb? Would it serve any purpose?

 

[snicklas]

Don’t want to hijack this post but have to ask, is an EGT gauge a thing if you don’t have a turbo? Is that dumb? Would it serve any purpose?

Absolutely. Actually, some would say that in an N/A Truck it is MORE important. An N/A can spike EGT's easier than a turbo one due to the decreased air flow. A "factory tuned" IDI will run right on the edge if you are monitoring it.... it takes less fuel to heat up the EGT's on an N/A vs a Turbo.....

 

[Stu Bailey]

Thanks @snicklas I’ve been thinking about that one for a while now lol good to know though!