Cascade Crew

doc76239 · Posted: Mon May 16, 2005 6:34 am Post subject: wtf need help

i have firbird 89 with 305 tpi, and 5 spd. when i rev engine to 4200rpm's it starts to misfire. like when i get on it from a stop in 1st gear, before i shift to second. Any ideas. i was thinking fuel pump. also i'm not holding fuel line pressure over night. Any help would be great.

Dewey316 · Posted: Mon May 16, 2005 6:45 am Post subject:

I would try to test the fuel pressure when you are driving it, if the pressure drops off at the upper RPMs, thats your problem.

chevymad · Posted: Mon May 16, 2005 8:51 pm Post subject:

Not many cars will hold fuel pressure overnight either. Spec is only like 5 minutes.

laegion · Member Joined: 08 May 2004 Posts: 96

what kind of gas are you running? how long since you did any kind of a tune-up? timing?

Sellmanb · Member Joined: 30 Nov 2004 Posts: 727 Location: Tigard, OR

When was the last time you did a full tuneup? Smile

84transam383 · Banned Joined: 25 Jan 2004 Posts: 431 Location: bend, or

when was the last tiem you saw a TPI car rev past 4200 rpms? Laughing

doc76239 · Posted: Sun May 29, 2005 11:17 pm Post subject: huh

so what are u saying? when i had my 10 bolt with 3.73 gears in it, i could rev to 5500 rpm in first, no problem.

Schultzy89GTA · Posted: Mon May 30, 2005 8:25 am Post subject:

Ignore the last comment doc, I think he was trying to be funny but it's hard to tell.

Anyway, have you had any luck getting more data on the problem? What is the fuel pressure when you are at WOT? You may need a longer hose on your guage to tell... I have a long FP guage that I tape to the windshield when I have had to test.

I have personally had two diff problems that kept me from spinning in the higher rpm's, fuel delivery and spark. I believe that is why people have been asking about the tuneup, spark plug wires, distributor, etc. If you could provide some more info I am sure that people will be able to help you diagnose the problem.

Cheers!

-Schultzy

Twilightoptics · Posted: Tue May 31, 2005 2:14 pm Post subject:

I had an '87 305 block with the peanut cam. I think they must have put cheaper springs in for those because it would float the valves at about 4200rpm and sound like misfires and junk flinging around. While my '85 305 with the better cam never did that to 5500rpm even!!

How many miles on it? They may be warn? It's a more indepth problem, less likely, but still a possability without actually hearing/feeling it happen.

rjmcgee · The Hammer Joined: 08 Jan 2004 Posts: 2328

Demon · Posted: Tue May 31, 2005 10:00 pm Post subject:

doc76239 · Posted: Wed Jun 01, 2005 7:25 pm Post subject: ????????????

i haven't even tried to test the fuel pressure at wot. my exhaust flange after the cats broke off, until i get the exhaust fixed i won't know any thing. I'm still thinking it's the fuel pump. cars has 95,000 miles on it. The only thing i changed at all on it was i put in split fire spark plugs. and shortly there after i started having problems. i've run splitfires in everything else i've had with no probs. it doesn't seem to matter if it's sitting still and i rev it up or if i'm moving, when the revs hit 4200, it starts miss firing, or what ever u want to call it. And yes i checked all the basics, firing order, bad wires etc. it pulls strong to 4100 and just goes crazy at 4200ish. dam things driving me nuts.
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