Ok guys, so I've got the classic hard start due to air intrusion. I bought this truck used in 2000 with 113k miles on it and have use it very infrequently, so mostly it has sat.
A few years back it developed the hard start symptoms and I replaced the glow plugs and return lines, which did not resolve the problem. It will start immediately if warm, but if it sits a few hours it will sputter a bit, and if it sits overnight it takes 10+ seconds of cranking, with strong batteries and a good starter.
This week, I've been trying to fix the issue, without success. Here's what I've done so far:
1. installed clear hose for the line between fuel pump housing and right front injector cap. (air bubbles would disappear after running for a short time.) btw, there is NOT a check-valve thingy in this one.
2. installed an electric fuel pump and removed mechanical pump (used block-off plate).
3. replaced o-rings and cap on rear injector passenger side because it was leaking a small amount. not leaking any longer.
4. ran hose from fuel pump to fuel filter housing, eliminating one "olive".
5. installed plug in the fuel filter housing outlet that goes to right front injector cap. (deleted) This was mainly a test to see if return lines are putting air in.
I have also ordered (not yet arrived) 2 olives for the hard line between filter housing and injection pump. This line is NOT leaking any fuel.
Ok, so after all this, I see basically zero improvement.
My observations:
1. On a cold start after sitting overnight, the engine does not come to life immediately then stall. It just cranks. This tells me that the injection lines have lost their prime somehow. The question is how???
2. Once started the engine generally runs well. It sometimes does some minor hunting during warm up, but it goes away before long. Engine purrs, has good power, clear exhaust at idle.
Questions:
1. Could this be a return line issue? Even if there is somehow error in the return line, I would think it should not cause the injector primary lines to lose prime. Unless maybe an injector is stuck open. But wouldn't that be noticeable when it is running?
2. Could it be a fuel supply issue? if there is air in the lines coming from the tank, well it doesn't seem like that should cause the injectors to lose prime either.
3. I do not see any visible fuel leaks anywhere. Is it common/possible that atmospheric pressure air is getting IN someplace although pressured fuel cannot get out?
4. Could this be an injection pump issue? I hope not....
5. What should I try next? I have the 2 olives on order. I'm considering replacing the fuel heater o-ring, or deleting the fuel heater. I haven't yet tried sucking fuel from a jerry can to eliminate possible supply issues.
I should also note that before this week the truck was sitting for years in a field. When I first tried to start it after installing electric pump I was still getting no fuel to injectors (verified by cracking them open). So I took the top cover off the injection pump and wiggled the spring mechanism back and forth and that seemed to unstick it and after that injectors were getting fuel and it would start/run.
Well I hope y'all have some suggestions. I've been reading through all the old threads I could find, but am still scratching my head.
A few years back it developed the hard start symptoms and I replaced the glow plugs and return lines, which did not resolve the problem. It will start immediately if warm, but if it sits a few hours it will sputter a bit, and if it sits overnight it takes 10+ seconds of cranking, with strong batteries and a good starter.
This week, I've been trying to fix the issue, without success. Here's what I've done so far:
1. installed clear hose for the line between fuel pump housing and right front injector cap. (air bubbles would disappear after running for a short time.) btw, there is NOT a check-valve thingy in this one.
2. installed an electric fuel pump and removed mechanical pump (used block-off plate).
3. replaced o-rings and cap on rear injector passenger side because it was leaking a small amount. not leaking any longer.
4. ran hose from fuel pump to fuel filter housing, eliminating one "olive".
5. installed plug in the fuel filter housing outlet that goes to right front injector cap. (deleted) This was mainly a test to see if return lines are putting air in.
I have also ordered (not yet arrived) 2 olives for the hard line between filter housing and injection pump. This line is NOT leaking any fuel.
Ok, so after all this, I see basically zero improvement.
My observations:
1. On a cold start after sitting overnight, the engine does not come to life immediately then stall. It just cranks. This tells me that the injection lines have lost their prime somehow. The question is how???
2. Once started the engine generally runs well. It sometimes does some minor hunting during warm up, but it goes away before long. Engine purrs, has good power, clear exhaust at idle.
Questions:
1. Could this be a return line issue? Even if there is somehow error in the return line, I would think it should not cause the injector primary lines to lose prime. Unless maybe an injector is stuck open. But wouldn't that be noticeable when it is running?
2. Could it be a fuel supply issue? if there is air in the lines coming from the tank, well it doesn't seem like that should cause the injectors to lose prime either.
3. I do not see any visible fuel leaks anywhere. Is it common/possible that atmospheric pressure air is getting IN someplace although pressured fuel cannot get out?
4. Could this be an injection pump issue? I hope not....
5. What should I try next? I have the 2 olives on order. I'm considering replacing the fuel heater o-ring, or deleting the fuel heater. I haven't yet tried sucking fuel from a jerry can to eliminate possible supply issues.
I should also note that before this week the truck was sitting for years in a field. When I first tried to start it after installing electric pump I was still getting no fuel to injectors (verified by cracking them open). So I took the top cover off the injection pump and wiggled the spring mechanism back and forth and that seemed to unstick it and after that injectors were getting fuel and it would start/run.
Well I hope y'all have some suggestions. I've been reading through all the old threads I could find, but am still scratching my head.