Will a bad FPR take out injectors?

TylerS

Gearhead
Would a bad FPR take out the injectors? My brother-in-law has had 3 sets of injectors in his truck (lb7). First were good to around 90k, then he had a local shop put new in but they didn't last and he had fuel in his crankcase. We figured that was bad job on that shop. He put in this last set everything was good 1500 miles and then #3 went bad. A different local shop said a bad FPR caused it. They scoped the cylinder and found piston had melted so it must of stuck open. I believe the other 3 injectors on that side checked out fine. Thoughts? Thanks
 

S Phinney

Active member
Aug 15, 2008
4,008
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Quncy, Fl
It is possible for it to contribute to premature failure but not in that short of a time I don't believe.

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nwodiesel

New member
Mar 29, 2014
78
0
0
Thunder Bay, Ontario, Canada
Would a bad FPR take out the injectors? My brother-in-law has had 3 sets of injectors in his truck (lb7). First were good to around 90k, then he had a local shop put new in but they didn't last and he had fuel in his crankcase. We figured that was bad job on that shop. He put in this last set everything was good 1500 miles and then #3 went bad. A different local shop said a bad FPR caused it. They scoped the cylinder and found piston had melted so it must of stuck open. I believe the other 3 injectors on that side checked out fine. Thoughts? Thanks

The oil in c case was probrably a result of the return line leaking. The biggest problem I find is that when you do the injectors.....you should replace the return line as well. Most don't. And don't be fooled there is no way to remove the hard lines without contaminating the injector with all the shit that falls out of the threads. moral of the story is change it all, and be very careful to keep shit clean......I mean hospital clean. Just my 2 cents, but I did my own injectors and upgraded the filter system......and that was 150,000 kms ago......all hiccup free.knock on wood

Not sure how the piston would have melted in a stuck open situation, as it wouldn't get a chance to heat up with all the fuel washing it.....
 

DAVe3283

Heavy & Slow
Sep 3, 2009
3,726
295
83
Boise, ID, USA
A stuck injector absolutely will melt a piston. Most/all of the injected fuel will burn with a stock size injector. They also don't always stick on 100% of the time, they just end up taking way too long to shut. So you ask for say 500 uS, and it actually stays on for 2500 uS. That's enough fuel to melt a piston, but not long enough to smoke much.

If the shop that did the 1st set of injectors didn't use new return line gaskets, that is probably where the fuel came from. I have never replaced a return line (except one that I had to cut off that had seized to the injector) and I've done 5 sets of LB7 injectors over 2 trucks and >> 200k miles, never had one leak. Just use new gaskets every time.

I would not think a FPR would be able to cause a single injector to fail. If it is shedding metal and sending that downstream, it would start taking out all the injectors. If the pressure relief valve is still on the rail, then even having the FPR stick open shouldn't be able to damage anything. What brand was the last set of injectors? A bad reman could have caused it to hang open.