What do I do next?

20

Asked by Sep 14, 2014 at 03:44 PM about the 1987 GMC Sierra

Question type: General

I have an 87 gmc high sierra 5.0. I
changed the fuel filter, fuel pump and
sending unit. Just put new plugs and
plug wires and the timing is set. It still
has hesitant take off and today it
backfired. Help please

6 Answers

148,625

Backfired through exhaust or back through intake?

1 out of 1 people think this is helpful.
20

Intake

1 out of 1 people think this is helpful.
148,625

Double check timing and make sure it's not too retarded..if in doubt advance it a little more than specs. Also double check the plug wires are on right..if even two are swapped it will run but a plug will ignite when an intake valve is open. After that, have to start looking at cam timing. I think it has a chain, but if high mileage it can actually stretch and jump a cog

2 out of 2 people think this is helpful.
148,625

Way excessive lean will also cause an induction backfire

1 out of 1 people think this is helpful.
148,625

The way I check cam timing in a pushrod engine is get #1 at about 10 BTDC compression stroke and look at...even feel rocker arms to be sure both valves are closed.

2 out of 2 people think this is helpful.
20

Ok thank you

1 out of 1 people think this is helpful.

Your Answer

Add photo

Related Questions

Sierra

Looking for a Used Sierra in your area?

CarGurus has 29 nationwide Sierra listings and the tools to find you a great deal.

ZIP:

Search GMC Sierra Questions

GMC Sierra Experts

#1 FordNut
FordNut
Reputation 210
#2 dandyoun
dandyoun
Reputation 110
#3 Js08016
Js08016
Reputation 90
View All

Related Models For Sale

Used GMC Sierra 1500
938 Great Deals out of 62,274 listings starting at $1,395
Used Ford F-150
2,700 Great Deals out of 212,349 listings starting at $1,000
Used Ford Mustang
363 Great Deals out of 44,490 listings starting at $1,000

Used Cars For Sale