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Ed Logsdon
New User
Sep 23, 2012, 1:55 PM
Post #1 of 2
(2310 views)
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I bought a 91 Isuzu pickup with multi-port fuel injection (2.6 L) in a not running condition. There was no fuel pressure and found the fuel pump to be defective. After replacing the in-tank fuel pump, thoroughly cleaning out the tank and adding a new in-line fuel filter I tried to start the engine. The engine pops, sputters and only starts with a rapid pumping on the gas peddle. When the engine catches it runs at a very high rpm under full throttle with no engine mis and then begins to sputter again loosing rpm and then dies out-right. It does not seem that there is a timing issue. I know that after the key is released there could be a loss of power to the fuel pump so I jumped it out with no improvement. The spark plugs are black with soot some more that the others leading me to believe that the injectors may need replacing; I have not run a drip test yet. I wonder if so much fuel is being dumped into the cylinders that the engine cannot run due to an over rich fuel to air mixture. I have also replaced the o2 sensor however, I still have an o2 warning light. I am going to get an Isuzu obd1 adapter for my code reader so I can look at the codes. I am also going to order a book with more information than the one I have. The truck has just over 200,000 thousand miles on it, and had been parked for around a year. The previous owner told me that when he quit driving the truck it was running but not very well with a gas smell.
I would like some input from someone who may have an idea as to what the problem may be.
Thanks for reading, Ed
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nickwarner
Veteran
/ Moderator
Sep 23, 2012, 6:30 PM
Post #2 of 2
(2269 views)
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Re: 91 Isuzu pickup
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You're on the right track with a rich condition. Do a fuel pressure bleed down test or an injector balance test if you have access to the tester. Previous owner drove it like that for a while til it simply wouldn't run. With such a rich condition I suspect a clogged cat. Hook up a vacuum gauge to the intake and run the engine at idle. Now accellerate to about 3000 RPM. If you see that gauge drop near zero thats an almost surefire indication of a clogged cat. If you have a backpressure tester you could use that too. If your cat is bad replace it, but make sure you also solve the rich condition and misfire that caused the cat to fail in the first place or the new one will fail as well.
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