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need to help out a friend


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dmac0923
Enthusiast

Apr 4, 2009, 8:00 PM

Post #1 of 6 (1516 views)
need to help out a friend Sign In

my buddy has a 1990 chevy 1500 SS with the 350 engine.

he is experiencing what he feels like an ignition miss at around 4300RPM only when the engine is fully warmed up. when the engine is cold, the truck runs like a top

no CEL codes come up

new cap,rotor,wires within last 6months
__________________________________________________
2015 Jeep Grand Cherokee
2002 Ford Ranger
2004 Toyota Corolla
1969 Ford Mustang Mach 1


Tom Greenleaf
Ultimate Carjunky / Moderator
Tom Greenleaf profile image

Apr 5, 2009, 6:01 AM

Post #2 of 6 (1510 views)
Re: need to help out a friend Sign In

What fuel delivery is used in this? Any guess of known miles?

T



dmac0923
Enthusiast

Apr 6, 2009, 9:08 AM

Post #3 of 6 (1501 views)
Re: need to help out a friend Sign In

hey tom,

his truck is Throttle body injected. he's close to 200,000 miles by now i believe.
__________________________________________________
2015 Jeep Grand Cherokee
2002 Ford Ranger
2004 Toyota Corolla
1969 Ford Mustang Mach 1


Tom Greenleaf
Ultimate Carjunky / Moderator
Tom Greenleaf profile image

Apr 6, 2009, 10:29 AM

Post #4 of 6 (1495 views)
Re: need to help out a friend Sign In

Eeek - 200k! I'ts ok - they can go tons more! I'd plain rule out a wicked loose timing chain by setting at TDC, - set that by turning crank bolt one way to TDC and watch dist rotor. Turn back the other way and see how many degrees the crank damper turns before dist rotor turns. Bet it's way over 5-6 degrees. When they get to 7-8 timing (valve mostly) just can't stay put.

By that I'm just envisioning the chain flying as high as it can at the higher RPMs just barely keeping the show going.

I know I'm an antique but back when with even American Iron engines if they needed water pumps at over 100k I would discuss replacing this with folks as you are almost there. The Chev should be fairly cheap - just the labor and dealing with any sticky nuts and bolts to get at them,

T



Double J
Veteran / Moderator
Double J profile image

Apr 6, 2009, 4:06 PM

Post #5 of 6 (1481 views)
Re: need to help out a friend Sign In

Just tossing my 4 cents in here too.

Check the distributor shaft reluctor magnet.
These have a tendency to crack and affect Ignition timing.(Known for it!)
Look for any cracks near the spline of the Shaft!


Guest
Anonymous Poster

Apr 6, 2009, 8:22 PM

Post #6 of 6 (1466 views)
Re: need to help out a friend Sign In

I'll toss out a couple of other quick check you can do on that system.

1st & easist to do is disconnect the egr valve vacuum line & take it for a drive to see if the prob disappears. Those are common for weak springs. Usually get an idle prob to but it's worth a shot..

2nd if it has o/d drop it into 3rd & if the prob goes away then it's in the TCC.

As others mentioned, check fuel pres... should be around 13 psi. I've seen run on way less & that could give you a high end problem... Those systems don't have a schrader valve, OTC makes an adaptor you pull in place of the fuel filter but if you don't have that you can always rig something...it is a low pressure system........






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