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Question

I''ve got a problem with my 95 chevy 1500 2wd. It''s got a 5.7, and auto trans. It has a problem with backfiring under a load, from around 2-3000 RPM. The motor and trans are fairly new, I rebuilt the distributer when I put the motor in, haven''t done anything to the injecters.

Submitted: 681 days and 3 hours ago.
Category: Chevy
Value: $15
Status: AWAITING CUSTOMER ACTION
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Optional Information

Optional Information:
1995 Chevrolet 1500 2wd 350

Already Tried:
The problem just started, haven't tried anything yet. I don't want to start blindly replacing parts that I can't afford. Seems to improve a little with more gas in the tank, might be my imagination.

Posted by Super Mechanic 681 days and 1 hours ago.

Info Request

Hi Studeguy, Supermechanic here. I just have a couple of questions about your truck.

Does it backfire through the intake or the exhaust?

Does the service engine light come on? If so, do you know the codes?

Do you know what the fuel pressure is?

Thanks.

681 days ago.

Reply

It's definitely backfiring through the intake. Tht service engine light has been coming on intermittently since before this problem started. The local parts store checked the code and said it indicated an oxygen sensor problem. I had replaced the oxygen sensor when I replaced the motor long before the light came on. I don't have any idea what the fuel pressure is. If it makes any difference, I've got a K&N filter setup instead of the stock airbox.(also installed when I changed the motor)

Accepted Answer

Hi 45, me again. It sounds like it may just be a bad ignition wire but we can't rule out fuel. If at all possible, check the fuel filter. I know how it is to check the pressure, (you need the adapters (not to mention a gauge). If the wires appear to be good, or not burned through by touching the exhaust manifold then it may be a good idea to just wet them and see if the problem gets noticeably worse.

Let's go for the easy stuff first, (although it can be more complicated) you don' t want to overlook anything. Let me know how it does. Thanx

Picture
Expert: Super Mechanic
Pos. Feedback: 98.6 %
Accepts: 
Answered: 1/12/2008

Master technician

29 yrs. exp., ASE master, cert. in G.M. electrical, a/c, susspension, brakes, electronic steering

680 days and 22 hours ago.

Reply

Supermechanic, I didn't find anything wrong with the ignition wires. I'm going to try a new fuel filter this afternoon. Do the think the injecters could be causing the problem?

Posted by Super Mechanic 680 days and 21 hours ago.

Info Request

When you take the fuel filter out you can see if it is clogged by blowing through it, (just tastes bad,,,lol)

Then you would want to know what the fuel pressure is.

Isn't that distributor that is run off the front of the crankshaft?

680 days and 19 hours ago.

Reply

Hi, This has the distributer at the back of the engine.(hard to get to) I think 95 is the last year they used the old style 350. I've got a filter, but won't be able to change it until tomorrow morning. I'll let you know then. Thanks!

Posted by Super Mechanic 680 days and 19 hours ago.

Info Request

Ok. You also may want to stop by an autozone store and have them see if there are any new codes in it. They do this at no charge. You may be getting an EST code or at least a lean running condition code, then we will know what direction to go in. thanx

679 days and 21 hours ago.

Reply

Hello again, I've changed the fuel filter. The old one was at least partially clogged. Blowing through the new one was a LOT easier than blowing through the old one. The scan at autozone indicated the oxygen sensor was making it run lean. The service engine light has been coming on for a couple months now, but it just started to run bad. Also, the problem seems to be worse when the tank is at 1/4 or below. I think I'm going to get the fuel pressure if I can. What is the pressure supposed to be at? Thanks, M.B.

Posted by Super Mechanic 679 days and 19 hours ago.

Answer

If I remember right it should be about 14psi. You might want to check with like, autozone they have that info,....just to be sure, thanks

679 days and 3 hours ago.

Reply

Hi, I drove the truck yesterday until it was almost empty, and it seemed to run fine. I think the fuel filter was the problem, but I'm still going to get the fuel pressure checked. I've got to take a XXX XXXX XXXX trip pulling a trailer in a month or so, and I don't want any surprises. Thanks, XXXX X.

Posted by Super Mechanic 679 days and 2 hours ago.

Info Request

I hope that's all it was. Let me know if it's not. Thanks

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