Just won't start but runs fine when starts

[Pastor Sinner]

DVolk: I well be adding a fuel pressure gauge on Monday, to check cranking, and running PSI. I built a lot of hotrods in my day, and the first thing we alway replaced first was the original fuel pump, as they are always a problem. I know that Diesels are a totally different system, I am looking into a Facet system as they are made for refers, and big boats that run on diesel. They have a built in check valve, they are MADE IN USA, you can get them in a lot of PSI ranges, I am looking at one the runs Min 12psi and Max 15psi. I will leave the stock lift pump in it's place and just bypass it, and just hook the Elec. one temporarily by the tank to rule out any air problems as it will self prime. I am afraid the IP is shot, but I want to know why and how to avoid the new one from doing the same thing. I have had this thing since 1994 and well maintained it and it only has 250K miles on it, I know guys that had theirs longer than me, work them to death, well over 500K miles and no problems.

 

[Pastor Sinner]

NIsaacs: Just trying to figure out how the darn thing went bad, as I always did good maintenance on it since I had it all the way back to 1994. When it sat for years I always started it about every 4 months and let it run for about 30 min just to keep it lubed up. I have a 1978 John Deere 310A backhoe with diesel and it sets a long time before I fire it up, and it starts right up every time. I just want to make sure what ever caused it to quit on me never happens again. I know guys who have 1st Gens with well over 500k miles on them beat them to death, and still running strong.

 

[NIsaacs]

NIsaacs: Just trying to figure out how the darn thing went bad, I just want to make sure what ever caused it to quit on me never happens again.

No problem, I can appreciate that, I like to make my equipment better, also, if I can. Keep in mind that mileage wise the truck is just getting broke in but years wise it is old. A $1200 pump after 23 years is really not bad. I have found these Cummins powered trucks are really economical to operate year in and year out so $1200 is only $50 a year.

Think back and see if you can remember any trauma that might have occurred regarding fuel quality. Such as an accidental dose of gas, an application of alcohol based fuel conditioner such as "Heat" fueling out of a ranch barrel/bucket full of water. Maybe even a hot engine that was taken to the car wash and washed. Cold water on hot aluminum is bad news. Then sometimes there is really no reason, stuff just fails early.

One other test I would do, is, the next time the truck is warm, run the engine at WOT for a bit and see if it runs smooth or rough and watch the exhaust pipe for white/black smoke. If it runs bad that's another sign the pump is sick, if it runs good that just makes you wonder and doubts will continue. I have replaced several over the years and I would always have a small doubt linger until the new pump went on and all was well again.

Nick

 

[ChrisWilliams]

That's exactly what I was getting at, when you bled it off it started. If you can reproduce that by bleeding off the air, then your IP is most likely fine, just have to find the air leak. It could be anywhere from the LP back, on the suction side. You have a 23 year old fuel system with metal lines that contains plastic and rubber o-rings that has been exposed to ULSD. There could be multiple air leaks to include a hole in the metal line.

All that said, now you have to find the air leak. If you can rig a temporary fuel tank to the LP, like a small boat tank, this will test the LP. Personally, for under $50, I would just get a new OEM style LP online. By the time you rig a test, you have spent a good part of $50 unless you have enough stuff laying around. Next, pressurize or vacuum test the line from the LP back to the tank. If you don't find it there, then it is in the tank pickup. There is a hard plastic line that runs to the bottom of the tank pickup. If you put an electric fuel pump near the tank, this will pressurize the line and show any leak, but it will not fix an air leak in the OEM LP unless you bypass it. Also, it will not fix a leak in the tank pickup line.

If you eliminate air and you still have a problem, then it is the IP. I had an air problem like this a few years back and I replaced the LP, then new lines and the tank pickup. My IP was bad as well, but the IP would not push any fuel to the injectors. I figured the air leak caused the IP to go. We were towing heavy and made it 350 miles before it shut down on the interstate. I didn't know at the time, but it had been starving for fuel the entire trip and I had no fuel pressure gauge. When I started fixing it, changed the LP and could never bleed out all the air bubbles which lead to replacing the lines and tank pickup. Two years ago, started having this problem again; found a rust hole in the bottom of my after market fuel water separator. I guess it did it's job, just need to change out the water separator filter more often.

 

[NIsaacs]

Ok Folks:
Truck runs great when I give a little shot of ether, won't start cold won't restart just seconds after turning off, cleans up after warmed up no misses, runs strong no lag or stalls, Just does not start
Pastor Sinner.
.

This tells me air is not an issue. If they suck air they will start and then die. On a warm restart, you can remove the lift pump, throw it away and it will still start with the fuel in the filter and pump. If there is an air leak between the injection pump and filter it will show up as a fuel leak. It has to be injection pump related.

Nick

Nick

 

[Pastor Sinner]

Nick: I am glad you are here to help me out. I never put gas in it or any additives, I plan on getting rebuilt after tax return comes, It runs fine after I take out for a spin no smoke what so ever, runs smooth. Before I changed out all of the injectors it was puffing a little bit of white smoke. When I pulled the injectors #4 cylinder was kinda black, so I am assuming it was the colporate; But after replacing them all it cleared up. Also when it happened to me last time, I just changed the LP and it worked fine, it just gradually started getting worse again; That is why I am going to temporarily install Elec. one just rule it out or tell me it's the problem again.
I think what the real problem is with the older Diesels is the newer fuel, need to start adding additives after I replace the pump.

 

[SierraTango]

If you crack the injectors are they all getting fuel? My '90 sits for long periods of time frequently and I have to crack the fuel lines at the injectors to make sure she's getting fuel each time I start her back up. Just a thought.

 

[Wayne M.]

P S, I do remember reading about seal material degeneration in the TDR way back when these trucks were in the run. As fuel additives changed to to emission requirements, the new brew would attack seals etc. maybe black beauty slept through all that and now is a victim. I refer to internal IP components.

 

[Pastor Sinner]

Sierra Tango: I replaced all the injectors. Wayne: That is what I am afraid of, hoping just replace all the O-rings and seals.

 

[Wayne M.]

Maybe one of the pump shops can just do a rebuild on yours and that would be economical.

 

[Pastor Sinner]

Wayne: In SLC there is Industrail Injection was told they could do it pretty reasonable. Just got to wait for the tax return.

 

[DVolk]

If it has 250 k and based the OEM lift pump that is your bidsue its a ware item and if you don't religousdly run fuerl additives to your fuel stuff wares out even with asdd itives and even if a rig sits it should not held out unless a leak develops my guess the dfiaphram has a pin hole in it

 

[Pastor Sinner]

Today I went and ran clear lines to a little fuel can sitting inside on top of the inner fender and just bumped the starter to get fuel, and it took for ever to get to pump up, but as I let it run the return fuel is making it's way back to the can ok. I added about a pint of injection cleaner to it and am going let it run for about an hour and go try and restart it to see what happens.

 

[DVolk]

Sounds like the lift pump is junk ,but to speed up the bleeding there is a 10 mm bolt byou can crack to bleed air just before the pump

 

[Pastor Sinner]

DVolk: I have done that, I am going to replace with elec. lift pump for test, to rule out any air problems.

 

[DVolk]

You might also have a crack in the injector lines

 

[Pastor Sinner]

It's a bad IP Going to need it rebuilt. I have no leaks, the Elec. fuel pump pumped up and stopped. I think newer fuel had something to do with it.

 

[Wayne M.]

Sorry PS. It'll have a new lease on life after that.

 

[Pastor Sinner]

Update on my 93, I rebuilt the IP the last couple of days and it fires right up now, just need to adjust timing better, and fuel screws. Hope it's better, will keep everyone posted. Thanks for all your help.
Pastor Sinner.

 

[Pastor Sinner]

New update: it still has problems, I believe the rotor head is shot as I see fuel spewing out of all the nozzles at the same time, not in sequence for timing like it should. need to be replaced after all.