1991 Chevrolet Cheyenne engine lopes while idling

MAJORTUSA

MEMBER
1991 CHEVROLET CHEYENNE
5.7L
V8
2WD
MANUAL
256,178 MILES

The engine lopes up and down while idling, is has stall while driving and was unable to start immediately, it did start again later but the loping continuous, I have replace the TPMS and Idle control solenoid with not significant results.

Sunday, July 26th, 2015 AT 1:58 PM

5 Replies

HMAC300

MECHANIC
48,601 POSTS

Check for a vacuum leak at base of tbi unit with choke cleaner and check other lines as well. If line soft going to map sensor replace it.

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Sunday, July 26th, 2015 AT 4:02 PM

MAJORTUSA

MEMBER
5 POSTS

Check for leaks couldn't find any, hoses to map sensor and all around TBI look in pretty good condition. Other suggestions?

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Wednesday, July 29th, 2015 AT 12:08 AM

HMAC300

MECHANIC
48,601 POSTS

You have to feel the hose not look at it if it is soft replace it. Scan for codes and check fuel pressure with a gauge 9-11 psi. Auto parts rent it.

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Wednesday, July 29th, 2015 AT 6:16 AM

MAJORTUSA

MEMBER
5 POSTS

I know that the hoses have to be feel and touch when I said they look in good shape I meant after visually and physically inspected them, I will check the fuel pressure and let you know.

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Wednesday, July 29th, 2015 AT 12:52 PM

HMAC300

MECHANIC
48,601 POSTS

Also check the ground for the HEI system also check canister purge valve for being stuck open it's the red valve on frame rh side of eng compartment. See if it is sending vacuum through valve on both sides it should only be one side from engine. It shold only work at 30 mph and above.