I have a 1992 Ford 2wd F-350 with a 5.8 motor that is running rough and blowing black smoke. It has new cap and rotor, new Champion spark plugs, timing is good, no vaccum leaks found, all sensors seem to be working, no check engine light, cylinder compression are all around 140lbs, fuel pressure is 12 primed and 40 running, air filter is new, any ideas why it is running rich?
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Help! 1992 5.8 runs rough
- Thread starter Corey Y
- Start date
jeepmauler
Well-Known Member
- Joined
- Oct 17, 2006
- Messages
- 2,064
check and see if the EGR system is functioning properly
Bodaciouscj7
Well-Known Member
Corey, check the injectors. If everything else has checked out I would be leaning toward one not closing properly.
TreeClimber
Well-Known Member
Does it have a vacuum line to the trans? Had a GM 350 / TH400 where the vacuum modulator had a slight tranny fluid leaking thru the modulator, and it was sucking the fluid all the way up to the engine and burning it. It blew lots of nasty smoke (although it did run pretty good).
Not saying this is your scenario, just another idea.
Not saying this is your scenario, just another idea.
zukkev
Cornfuzzled yet again...
12psi primed??? and then 40 running??? something isn't right there....should prime to 40, then run at around 32-35 psi (regulated pressure)....also, pull the vacuum line at the regulator and see if it's leaking fuel thru the vacuum port due to a ruptured diaphram....it can still regulate properly, but be leaking! Been there, seen that many times....:awesomework:
Totalled
That Ford Guy
Fpr....
If I cycle the ignition 3 times it primes to 40, start the truck and it runs at 35-40 psi depending on RPM. Pulled the vaccum line and there is no fuel.
How can I test the injectors? I was looking at the Dr. Injector website today, they sonic clean and flow test. Anyone ever used them?
Bodaciouscj7
Well-Known Member
It should hit full pressure when it first primes. How long does it take for the pressure to bleed down not running. Mitchell states 30-45PSI for KOEO and 35-45 for KOER.
We use Dr Injector for all of our injector cleaning/rebuilds (they are 1/4 mile from us). As for just checking to see if you have one stuck open hopefully someone knows another way than the way I check GM's cause it will suck to do on a Ford. The only way I have done it is to pull the rails with the injectors still in the rails and pressurize them it and look for 1 dripping or spraying. Make sure you check everything else first cause Ford intakes suck
We use Dr Injector for all of our injector cleaning/rebuilds (they are 1/4 mile from us). As for just checking to see if you have one stuck open hopefully someone knows another way than the way I check GM's cause it will suck to do on a Ford. The only way I have done it is to pull the rails with the injectors still in the rails and pressurize them it and look for 1 dripping or spraying. Make sure you check everything else first cause Ford intakes suck
Took the injectors in and they were in pretty good shape, had them cleaned and put back in with new seals. I also put on a new fuel pressure regulator from Ford along with new valve cover gaskets because the cork ones were hard and leaking. Still runs rough and dies after it warms up. Every time I take the plugs out they are black or wet from fuel. I cant figure out the why it is still running crappy.
TreeClimber
Well-Known Member
Took the injectors in and they were in pretty good shape, had them cleaned and put back in with new seals. I also put on a new fuel pressure regulator from Ford along with new valve cover gaskets because the cork ones were hard and leaking. Still runs rough and dies after it warms up. Every time I take the plugs out they are black or wet from fuel. I cant figure out the why it is still running crappy.
Have you replaced the temp sender. If the motor temp sender is bad, the motor will think it's running cold, and enrich the fuel mixture. A bad sender will cause too much fuel to get dumped.
As with all fuel injection setups, getting live data will tell you what the system is doing. You should be able to see the O2 sensor work, the temp sender work, etc.
Probably worth the money to take it to a shop, before you throw parts at it.
Tony
The guy at Dr Injector said that could be the issue, I am towing it down to Performance Prep tomorrow to let them figure it out.
Totalled
That Ford Guy
Have you had the TFI modual tested?
No
http://www.epinions.com/auto-review-2771-1DEC7FB7-39E554B7-prod4 Hmmm.
I replaced the coolant temp sensor and it ran alot better. It had a plastic Chinese one and I put in a FOMOCO brass sending unit. I drove it to a shop that specializes in fuel injection and electrical problems. It still ran like crap at idle but above 1200rpm it is smooth. They are going to look at it Monday. The check engine light came on while I was driving it to the shop.
skinny_pedal
Well-Known Member
Have you left the fuel pressure gauge on the truck and drive it?
TreeClimber
Well-Known Member
Fuel Injected rigs tend to have Electric Fuel Pumps, which seldom fail during idle conditions, then return to operational when running higher RPMs.
Normally the reverse is true. As the pump dies, it develops less pressure, which allows nice idle, but as demands on the engine require more fuel, the pump is unable to deliver, and mid - high load range runability concerns develop
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skinny_pedal
Well-Known Member
Misread the 1200rpm part. Trust me, I know how a fuel pump works:;
They get 2.5 hours for diagnostics, no more. Hopefully they can tell me what is wrong with it, if not it will be on Craigslist.
