![]() |
Register or Log In To remove these advertisements. |
|
|
![]() |
|
Thread Tools | Display Modes |
![]() |
#1 |
Registered User
Join Date: Apr 2005
Posts: 2
|
![]()
Hey guys
We brought the truck to our mechanic 3 times and he cant find the problem. The whole ignition is new. Plugs, wires, cap, rotor, coil. I guess he put in a newer style of cap and rotor with the coil outside of the cap instead of ontop. well anyways it sputters like crazy. Well. I shoudl say stumbles..? Basically it feels like from time to time its not running on all 8 cylinders. HUGE power drop and we tow our horse trailer with it. It just happend recently about 4 months ago. The engine will run strong when its cold. But once it warms up it starts stumbling. Almost for the whole day it will run like crap. Now and then it will run great. almost like someone fliped on a switch and then it runs good. Then this switch gets flipped off and the engine runs like crap. Anyone have this problem before? Its not the fuel pump or fuel filter I have had fuel problems in the past and this deffinatly isnt a fuel problem. Unless im wrong. The truck it throttle body Fuel Injected. Im guessing these have a MAP sensor? thanks guys. Hope to hear from you! Justin |
![]() |
![]() |
![]() |
#2 | |
Registered User
Join Date: Sep 2004
Location: Elkins, West Virginia
Posts: 2,542
|
try the map sensor, and the throttle position sensor.....(about $30 each at advance auto)....there both located side by side, on the left side of the throttle body, and only take 5 minutes each to change
believe it or not, a bad O2 sensor can do this as well ![]() is your check engine light on? Quote:
__________________
1987 350 TBI lowered 5/7 Last edited by bigarmzz; 04-22-2005 at 08:01 AM. |
|
![]() |
![]() |
![]() |
#3 |
Professional Beer Tester
Join Date: Aug 2004
Location: Louisiana
Posts: 453
|
Justin, you might also try unhooking the EGR valve to rule that out.
60-66 Nut
__________________
60 Ford F100 Custom Cab 61 Apache Short Fleetside 64 C10 Short Stepside 65 C80 409 V8 5spd(X-Firetruck) 83 GMC 350 Olds Diesel 85 GMC Short Bed 86 GMC Short Bed 90 GMC R3500 Crew Cab 92 GMC 1500 |
![]() |
![]() |
![]() |
#4 |
OL BLUU
![]() Join Date: Mar 2004
Location: WICHITA, KS.
Posts: 1,065
|
From my personal experience I will tell you that it is the distributor assy. It seems that the lower bearing on the shaft wears out and it makes it off balance and wobbles. In turn it misses on the contact points on the distributor cap. I had a 92' p/u w 80k miles, a 95' Tahoe w 75K miles, and another 95' Tahoe with 90K miles. ALL of these vehicles I had the same "missing" problem (ALL 350 F.I.)..... I had the distributor replaced, and the problem went away. It is a very irritating problem, you may call a local GMC shop and they may tell you the samething. Good luck.....
|
![]() |
![]() |
![]() |
#5 |
OL BLUU
![]() Join Date: Mar 2004
Location: WICHITA, KS.
Posts: 1,065
|
BTW: mine ran EXCELLENT when the Engines were COLD.... and as soon as they warmed up they went to crap as well.
|
![]() |
![]() |
![]() |
#6 |
Registered User
Join Date: Apr 2005
Posts: 2
|
Hey thanks alot guys. I will check all those out. I have been going nuts trying to figure it out. To bad its not a rotary 13B engine. I know them. lol.
How much good is it to throw in a MSD HEI distributer? will it help power at all? or is it basically a waste without other upgrades? Justin |
![]() |
![]() |
![]() |
#7 |
STILL PLAYS WITH TRUX
Join Date: Nov 2002
Location: Melbourne, Fla.
Posts: 2,764
|
![]()
When you do the distributor id'e check all the rubber fittings that hook up to the map, egr, and throttle body they become dry rotted and sometimes this occurs on the lower side of them and from a glance they may look good but can be junk and if there sucking air you will have a rough running engine.
Good luck |
![]() |
![]() |
![]() |
#8 |
Registered User
Join Date: Sep 2004
Location: Elkins, West Virginia
Posts: 2,542
|
i just had a friend come over today with his 87....same problem....i went over and over what i thought it could be....
ended up being the idle control valve...($27 at advance)...probably saved him $100 worth of diagnostic fees ![]()
__________________
1987 350 TBI lowered 5/7 |
![]() |
![]() |
![]() |
Bookmarks |
Thread Tools | |
Display Modes | |
|
|