need input
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Joined: Apr 2014
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need input
O.K., searched this site for an answer, sorry,maybe I missed it. Here's my problem. I have a '94 F250 2wd 7.3 IDI,auto. 355000 miles. Replaced injectors and return lines and it ran like a new truck for about 2 weeks.Wife was headed to the store when she heard a loud pop and smelled fuel,started running like crap at that point. The return cap on #7 injector was cracked and spraying fuel out, plus pushing fuel out of the rear tank. It was running rough and would idle with the rpm's up, but let off and she would stall.Any ideas would be appreciated.
Post Fiend
Joined: Nov 2005
Posts: 7,437
Likes: 4
From: Charles Town, W bygod Va
Obviously you need to replace the broken cap. Did you replace them with the return lines? I've seen some some kits that come with the caps but have heard they aren't very high quality compared to oem. It sounds like you could have a problem with the tank selector system returning to the wrong tank... Maybe it's causing an overpressuring of the return system.
Lead Driver
Joined: Apr 2008
Posts: 6,944
Likes: 13
So it made an audible pop sound, and gushing fuel at the fuel tank? Id say the injector came apart / catastrophic failure allowing cylinder pressure into the return line. Pull the injector and take a looksy at it.
Postmaster
Joined: Dec 2011
Posts: 3,860
Likes: 7
Could the return line be clogged, or the selector valve fail?
Remember, our IPs work on pressure differential... if your return line got blocked somehow, the pressure would equalize and the IP wouldn't run well at all.
Also, pressurized return lines might explain a broken cap, but I'd usually expect the o-rings to fail first.
Injector wise, remember: the amount of fuel going into it /total/ is very small. The entire output of the IP for one cyl could easily go into the cap and return to the tank -- sure the pressure is at 2Kpsi when it's injected... but if you give it anywhere to go, that pressure will be near zero. It's only the massive spring in the injector keeping it closed that allows the pressure to rise.
Remember, our IPs work on pressure differential... if your return line got blocked somehow, the pressure would equalize and the IP wouldn't run well at all.
Also, pressurized return lines might explain a broken cap, but I'd usually expect the o-rings to fail first.
Injector wise, remember: the amount of fuel going into it /total/ is very small. The entire output of the IP for one cyl could easily go into the cap and return to the tank -- sure the pressure is at 2Kpsi when it's injected... but if you give it anywhere to go, that pressure will be near zero. It's only the massive spring in the injector keeping it closed that allows the pressure to rise.
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