Injectors fail, no warning. Why?

[Fandini]

Truck was running like a champ Thursday. Went out Friday morning and cranked it and absolutly nothing when tunring over, not even a partial fire on any cylinders! Cranked it serveral times for a couple of minutes for 5 to 10 seconds each time. Went inside for about 5 min then came out and tried again. Held the starter for about 15 seconds and got a partial cylinder fire. So, continued to crank with partial cylinder fires until it got enough to start. Finally started runing on about maybe 4 or 5 cylinders and no smoke coming out of tailpipe. After driving for about a minute the misses gradually cleared up until it ran perfectly. Drove for about 10 minutes until I got to the job. Sat about 15 or 20 minutes until I went out to start again. Cranked about 3 times longer than normal but finally started and ran roughly again for about 20seconds until it cleared up. Started 3 more times each time with the same results until the 3rd time it never cleared up and would only run about 5 to 10 mph. drove straight to dealership. Mechanic checked it out, fuel supply etc. and found 3 failing injectors. Here is what puzzles me, if only 3 injectors were failing why did none of the cylinders fire at all when I first cranked it Friday morning? Seems like it would have at least fired roughly with 5 of the injectors working.

Any thoughts?

[forddieseldoctor]

Have your mechanic monitor the fimc voltage and make sure that it doesn't drop below 45 volts. Did he check fuel pressure? I had one this last week that only had 10 psi of fuel pressure and it only took out one injector.

[Fandini]

Originally Posted by forddieseldoctor

Have your mechanic monitor the fimc voltage and make sure that it doesn't drop below 45 volts. Did he check fuel pressure? I had one this last week that only had 10 psi of fuel pressure and it only took out one injector.

I know he had it hooked up to his laptop and said the FICM checked out. He was puzzled as to why it quit, especially since he just had it for a week for a couple other things (oil leak, bad glow plug, and small fuel leak) and it was running perfectly. As a matter of fact he was saying what a great running engine my truck had in it. Just picked it up the morning before and was running beautifully that entire day. Checked fuel filters I know and ran it with computer hooked up. I'm pretty sure he had some gauges hooked up to the engine mounted fuel filter but I could be wrong. Is it possible for the fuel pressure to have dropped that morning when it wouldn't fire at all and then come back up before he hooked up to the computer. I know it had a small fuel leak at the engine mounted filter housing that he fixed when he had it last time. Leaked for several months before it was noticed and fixed but it was very small and hardly noticeable.

I do run Scheaffers diesel fuel additive to lube and keep injectors clean, would've thought that would've helped.

[Fandini]

Just givin' this a bump in case the doc or somebody else has seen this?

[forddieseldoctor]

The new fuel pressure tester from Ford is a gauge with a drain hose that runs back to the tank with an orifice in it so that when you open up the valve i simulates full load on the fuel system. The truck I had the other day had 45 psi with the valve closed, but when you opened up the valve the pressure dropped to 10 psi.Low fuel pressure will tear up injectors. There is another issue that is out there where there is an injector that allows combustion gasses back into the fuel rail, but the usual symptoms of that are it runs good when you first start and then it gets worse the longer it runs and it usually stays all on one bank.

[Fandini]

Thanks for the reply and the heads up doc. Will stop by first thing tommorrow morning and check. I'm pretty sure he had a gauge on it. This guy has been doing this a really long time and is considered to be tops around here.
But, we all learn new stuff no matter how long we've been doing something, I know I do and I've been in my field for almost 30 years. The biggest thing that puzzles me is the fact that when I first tried to start it Friday morning not 1 single cylinder fired! It was like pulling all the spark plug wires off a gasser and cranking it. When it did fire there was not a wisp of smoke. Worried about this because my warranty runs out in July and I've been on top of ALL my maint. since day 1

[Fandini]

By the way, is replacing injectors a cab off repair?

[forddieseldoctor]

No it's a fairly simple repair.

[zackisbell]

Whats normal labor cost for replacing one injector, on passenger side?

[Fandini]

Don't know what injector replacement cost, mine were done under warranty. I've head the injectors alone are about $400.00.

As far as the injector problem on my truck, everything tested out good, fuel pressure 55, FICM good, etc. Head studs appeared to be improperly torqued and torqued without torqueing lube according to mechanic. Said there was no evidence of lube used when studs were installed by previous mechanic and when replacing a valve cover gasket and I think even a head gasket for an oil leak just prior to the injector problem he had to take the studs all the way out and put them in a vice to remove the nuts from them. I know very little about the proper procedures here reguarding the ARP studs but I do know that a torquing lube is supposed to be used when torquing these nuts on the studs to acheive proper clamping tension. He doesn't know what caused the injectors to fail but thinks it's possible that some coolant got into the oil and caused a problem with the injectors by coolant cantaimination in the oil since the head bolts appeared to be improperly tightened. So, he removed all head studs, reinstalled and torqued with torqueing lube to 250 ft lbs, then changed my oil. Even though the truck is still under warranty that cost me about $300.00 because ARP head studs are not an OEM part which sucked but I understand. The oil change was kind of a bite because I had just changed the oil less than 300 miles prior to all this happening using my precious Scheaffers 15w-40,but hey that was free because it was warranted . Everything seems to be fine now. I still have a sample of oil from the last change that I didn't send of to be analyzed but I'm going to do that this week.

I have know way of knowing what any of the mechanics do or don't do or if what they tell me is the truth but I have to place my trust in them. It does make you a little wary when you leave your vehicle with one guy that you trust 100% and then down the road another mechanic that you trust 100% tells you that the last guy you trusted didn't do the job right. Puts you in a position of feeling like you can't believe anyone. One reason I started working on my own toys was because the powersport guys were telling me lies and ripping me off. I just don't see the diesel mechanics I trust doing this but it still leaves me a little uneasy.

Anybody have any thoughts on my experience with improperly torqued head bolts, or coolant in the oil causing injector failure. Any techs input would be great.

Thanks!!