Immediate start, then stalling - Diesel Forum

hunterb2 · 09-22-2006, 08:39 PM

Hi everyone,

I'm having a problem at start-up. The engine will fire up very quickly, in fact better than it ever has, but will then immediately start to run very rough or may actually stall. If it does stall it's a beast to get running again. I suspect it is an air leak somewhere. I did run it very low in fuel shortly before this happened. Not out of fuel, but judging by the guage it must have been on fumes.

Is this most likely an air leak problem and, if so, what is the best procedure for tracking it down. I have done a search but cannot seem to find anything although I know I've read about it on this site before.

Any help would be appreciated [img]/ubbthreads/images/graemlins/smile.gif[/img]

cdnsarguy · 09-22-2006, 10:09 PM

Put a clear line between the fuel filter header check valve and the #1 injector. Do the same on the IP to #2 line, ensure there is a loop in the line. Start and run the engine go for a drive with rpms up to 2500-3000 to clear the lines. Observe the clear lines after shutdown to see if any air intrusion is seen and from which way.

Do a pressure and flow test of the fuel pump at the Schrader valve on the filter header (FSS- fuel shutoff solenoid disconnected on IP). Remove the tire valve core and hook a hose and pressure guage on it should see 4-6 psi when cranking. Then do a fuel quantity test same place, should see 1/3 pint in 10 seconds of engine cranking, route fuel to a suitable container with a hose.

hunterb2 · 09-22-2006, 10:37 PM

Thanks Pete. I was hoping you were watching. I'll try the clear line trick. I know in the past when I have run it low on fuel it will run rough or sometimes stall on start up for a bit afterward. It just seems that this time it is taking a long time to sort itself out.

Thanks for the reply.

Bruce

cdnsarguy · 09-23-2006, 09:33 AM

Have you done any work on the engine at all lately.

hunterb2 · 09-23-2006, 12:07 PM

Hi Pete,

No work on the motor lately. I replaced the fuel pump 2 years ago as well as installing a return line kit. Replaced fuel filter and Racor filter in April. One thing that did happen is the front tank started leaking in the summer so I ran it down to basically empty and have been using the rear tank exclusively since. The only anomoly in the last while was running it very low on fuel (oops).

I tried to find clear tubing last night but couldn't find anything other than quite stiff line that I didn't think would seal on the fittings. Who carries clear, soft hose?

I'm taking the truck for a run on the highway today. Maybe that will purge any air that may still be lurking in the system from running too low on fuel, if that's even possible.

Thanks again. I'll let you know what happens.

Bruce

BuilderBob · 09-23-2006, 08:12 PM

[ QUOTE ]
I replaced the fuel pump 2 years ago

[/ QUOTE ]

Don't assume it to be good.

jchipper · 09-23-2006, 11:15 PM

I had that same prob about 2 weeks after I bought mine, I searched and searched and could find nothing took it to the Diesel shop and he found it in 30 secs :P the hard fuel line where it goes by the exhaust manafold had a hole worn through it it was just a small pin hole but small enough to let air in when it was shut off, so I'd suggest checking the fuel line everywhere feel it cuz you'll feel if it has a flat spot from viberating. I took a pipe cutter cut the fuel line and replaced it with some rubber fuel line tied it to the frame so it is away from the frame and it works great now!

just my thoughts.

cdnsarguy · 09-24-2006, 09:11 AM

Home Depot may have it, Skidoo or Quad dealers may have slightly tinted fuel line.

Check the rubber line to the lift pump for cracks, it usually has to have a pigtail curl from the steel line to LPump, also check the steel line for wear back to the FSV. The filter header line in and the IP line (steel) have rubber seals under the cap nuts. See my gallery..

hunterb2 · 09-24-2006, 10:55 PM

Well I think I solved it. I changed a couple of suspect lookng O-rings, removed and replaced the fuel filter and the racor, snugged up the valve on the filter header and then took it for a run over a mountain pass where sustained 3000 RPM's. One or more of those must have been the problem because it seems to be fine now. I'll know for sure in a day or two.

Thanks for the replies.

Bruce