4.3 vortec 4x4 engine / fuel issue

[BlazerLT]

Did you replace the cap and rotor?

[pauper_72]

Hi,
Yup. I changed the pickup coil, plugs, wires, o2 sensors, fuel pressure regulator, cap / rotor and ran injector cleaner through it.

None of which has changed the way this truck runs the slightest bit.

I read somewhere about faulty CPI / nutkit and / or central sequential fuel injection.

Any thoughts? Or anyone had experience with these?

[rlith]

You run CSFI not CPI (Same principal but CFI is sequentially injected vs batch fired)... You said you changed the fuel regulator, that's part of the injection unit itself, it's not seperate from the injector, so you replaced the injector itself?

Did you also changed the coil itself or just the ignition module? Have you checked the crank position sensor? Just some things for you to look at... One other thing.... Start your truck in the dark and look in the plugs/cap/coil areas and see if you see any arcing going on.

[ALMB~Nova]

I know this may sound stupid, but I have encountered this before on other cars. Check or replace the coolant temp sensor. If the sensor is reading wrong it could be telling the computer to dump more fuel than necessary. Usually you wont notice any problem when its warmes up but when its cold it will act like its flooded. try unplugging it and see what happens. JUst a thought.

[pauper_72]

Actually, the fuel pressure regulator was not a "part" of the injector. It was held in place by a C clip. Remove the clip and pop out the regulator. But, the one odd thing on that was no apparent vacuum line to the regulator when I removed it, so I did not search extensively for one to go on the replacement. I thought I read somewhere that some are "self contained" (or something like that) vacuum's. There are no arcs, already checked.

I tapped out the rivet in the stock ignition module and replaced that. I will jot down the other ideas and let ya know what happens. Crank sensor and coolant temp sensor and post results.

THANKS for being patient guys!
Cynthia

[tomcat ted]

Originally Posted by pauper_72

Hi again.
OK, FINALLY found the fuel pressure regulator (who's bright idea was THAT???) and changed it.

It did not help AT ALL. The truck will run great at RPM's above 1800 FOREVER with no MIL codes. Under that, it chugs and misses for about 4 minutes before 2 PO300 codes come back.

Any thoughts?

I had a similar problem with a 94 vortech. Remove the EGR and clean
it. Make sure the valve has the full range of travel without hanging
up. Was there any fuel beneath the plenum on the right side? The computer is changing fuel values because of the lean condition in the plenum.You should also note that the power brakes appear almost none existant at low speeds. Put a vacumn gage on the intake and look for
low readings.You may have more than one problem but eliminate the easiest first.

[DEUCE-IS-WILD]

[pauper_72,just found this site and was just wondering if you ever got the p0300 problem fixed...i am in the middle of the same issue on the kids 98 blazer and i am about to pour a can of gas on it and be done with it.

[pauper_72]

In a way, yes...I found the solution...Some guy just HAD to have my truck, so I sold it for 500.00!!

I know that wont help you, but I do wish you luck. I will NEVER own a used 4.3 again!

Sorry for your troubles but here is to your success in '06!

[rlith]

Originally Posted by pauper_72

In a way, yes...I found the solution...Some guy just HAD to have my truck, so I sold it for 500.00!!

I know that wont help you, but I do wish you luck. I will NEVER own a used 4.3 again!

Sorry for your troubles but here is to your success in '06!

Christ, you sold a 99 truck for 500 bux????! If the body alone was good, I would have easily given you double that!

[yotawithchevypower]

Originally Posted by rlith

Christ, you sold a 99 truck for 500 bux????! If the body alone was good, I would have easily given you double that!

Last weeked I was having the same issues, although the engine is in an 87 toyota pickup. The problem ended up being that the pickup hose in the gas tank was collapsing on itself. Even with the problem, at idle the fuel pressure was only 55, but when you stepped on the gas the suction from the fuel pump would cause the hose to collapse on itself.

That really really sucks that you gave up on that car. You're not a mechanic and neither am I, but you could've learned more buy solving the problem.