1995 Chevy Van

DAVEMCK383CI

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1995 CHEVROLET VAN

Engine Performance problem
1995 Chevy Van 6 cyl Two Wheel Drive Automatic

I have a 1995 p30 purolator van with a 4.3 vortec engine. Recently I had the engine replaced with a newer 4.3 engine 8 bolt intake, this engine did not have a normal fi intake on it, i'm pretty sure it is a marine or industrial engine. My problem is that it will not run very well ie back firing through carb lack of power.I have replaced everything I can think of aswell as play with timing nothing works. HELP

6 Replies

MERLIN2021

MECHANIC
17,250 POSTS

Compression test this one, backfiring thru the intake can mean a bad cam, or broken valve spring. Or burned valve.

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Friday, March 5th, 2010 AT 5:42 PM

DAVEMCK383CI

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I have done the comp test all are at 120.I have also installed all new sensors on engine temp, tps, new injectors, 02, ignition coil, cap@ rotor, played with timing, I have even gone as far as the ecu.I am getting differant information on the initial timing not sure exactly what it is suposed to be.I have tried 0 with wire unplugged, I have tried 10 plugged in and almost every combo in between. Is there a big differance between the two engines that I am not seeing?

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Friday, March 5th, 2010 AT 6:41 PM

MERLIN2021

MECHANIC
17,250 POSTS

If you can figure out what it came out of, you could get specific info, but a 4.3 is a 4.3...Did you try looking for codes yet? Cross the A and B terminals of the data link connector under the dash, turn the key on, and count the flashes.

PROCEDURES FOR READING GM FLASH CODES
1. Turn the ignition switch ON but do not start the engine.
2. The "CHECK ENGINE" light come on indicating the bulb is working. If the light fails to come on, the bulb may be burned
out or there may be a problem in the Check Engine light circuit.
3. Locate the diagnostic connector for the computer. It is usually located under the instrument panel near the steering
column. Insert a jumper between the "TEST" and "GROUND" terminals.
CAUTION: Refer to a shop manual for the proper terminal locations. Jumping the wrong terminals may cause damage to the
computer system!
4. The Check Engine should now flash. The first code should be a code 12 (Flash, Pause, Flash Flash). Code 12 will repeat
two times.
If any other trouble codes are in the computer's memory, they will be displayed in numerical order starting with the lowest
number, and repeat three times. The codes will continue to repeat as long as the test terminal remains grounded.
NOTE: BE SURE TO WRITE DOWN ANY CODES THAT ARE PRESENT
NOTE: GM may use the same code number for different faults on different models of vehicles. That's why some code
numbers list more than one possible cause.
5. To exit diagnostic mode, turn ignition switch off and remove the jumper.
HOW TO CLEAR TROUBLE CODES
Trouble codes on most older vehicles can be cleared by removing battery voltage from the computer for at least 10 seconds.
Make sure the ignition switch is OFF, then remove the computer fuse from the fuse panel. Disconnecting the battery will also
work, but doing so will also cause the loss of stored information and presets in other electronic accessories such as the
radio, climate control system, memory seats, etc. Disconnecting the battery can also cause the computer to forget long term
fuel calibration adjustments, and may affect the operation of an electronic transmission until the computer can "relearn" the
shift points.
The preferred method of clearing trouble codes is to use a scan tool.

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Saturday, March 6th, 2010 AT 10:15 AM

DAVEMCK383CI

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I'm sure it must be frusterating for you guy's at times, but i'm not asking for code reading advice as I have a reader. What I am asking is there a diff between the two engines 95 vehichle vortec and the 96 or 8 bolt intake marine industrial engine. And if so what are they and what is the initial timing to be set at. The only code I am getting is a trans code and that has nothing to do with the way it is running. The new engine came to me with a 2 barrel cast iron intake and that would tell me that it was designated for one of the two previously mentioned applications. Being an 8 bolt intake I had to do some homework to make the tbi setup work as there is not an intake that will accept tbi on an 8 bolt head. There are no vaccum leaks the plugs are for the new engine all sensors have been replaced. When I set the timing with the wire unplugged to 0 and plug the wire back in after I turn off the engine the computer takes timing out and retards the engine to the point of backfire through the carb. This I think would tell me that there is something wrong with the computer so I find two more ecu's, same thing for one and the other it runs better but the converter locks up and only has second gear not so good for converter or trans. Again have done homework on ecu all are for my application I think at least have the correct service code. If anyone is working on this please send me a masseage saying so as I am needing to get this completted asap

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Saturday, March 6th, 2010 AT 11:41 AM

MERLIN2021

MECHANIC
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I dont know a lot about marine engines. But doesnt the salt water run thru the intake? Did you swap the manifolds? I really have never heard of putting a boat engine into a truck. Sorry.