Bought a beater for a song and a dance.....

[dodgeguy]

Picked up an old '85 GMC 1/2t as a beater, it sat for most of last year, and plan on buying an older tent trailer for spring to go camping and quadding next summer. Anyways, it's a 5L 350 turbo trans. Had the quad in the back and it hesitated big time on the hiway 11 hill west of RD was down to 80kmh. Let my foot off the throttle a few times seemed to be ok :dand sped up to 90kmh then would bog again down to 80kmh. Dropped the quad and it runs very good, until I go to pass someone then it hesitates and bogs again until I left let off the throttle. I am a Fuel injection kinda guy, and this truck is carbed...threw some gas-line antifreeze in it, that seemed to help a bit. Its at half tank today so gonna throw some fuel conditioner in it and fill it. It had a 1/4 tank when I picked it up and I immediately filled it. Air filter is changed, fuel filter is ok, changed the oil...perhaps it still has some rank gas in it?? OR will the carb need to be rebuilt? It starts quite well, and idles really good too. Just wondering what some opinions are....as in the spring I will be asking it to haul around 2500# of camping and quadding crap....lol

 

[DaveB]

Fuel pump output and pressure?

 

[AreWeThereYet]

Accelerator pump, when you step on the throttle, a linkage rod is suppose to push it down,.. you have an air leak or dumping too much fuel. Need to rebuild the carb. Too bad I had a 4 barrel quadrajet I let go a short while ago.

Pull you air cleaner off and I believe it is on the back passenger side,.. been about 15yrs since I worked on a carb job so the memory is a little thin

 

[dodgeguy]

Fuel pump output and pressure?

Yep am wondering that too...lol bad as it is to say it without a fuel rail i dunno how to check it....(hangs head in shame) haha

 

[dodgeguy]

Accelerator pump, when you step on the throttle, a linkage rod is suppose to push it down,.. you have an air leak or dumping too much fuel. Need to rebuild the carb. Too bad I had a 4 barrel quadrajet I let go a short while ago.

Pull you air cleaner off and I believe it is on the back passenger side,.. been about 15yrs since I worked on a carb job so the memory is a little thin

Yeah, the guy I got the truck off of remarked I MAY have to be rebuilt....so is it ran by vacuum? Cuz I don't hear a leak!?!?! I have Tuesday Off and will take it apart a bit to get a good look. Now that the roads are better, no weight in the back makes her tail happy...lol, I will see if its smokin black or not...

 

[DaveB]

Pump is a mechanical deal on the front of the motor (if is's a typical SBC)...unhook the feed line to the carb, unhook the HEI so it doesn't start...put a cup under the line and turn it over. There's a spec for how much fuel is pumped into the cup for how many seconds of cranking....

How would i check to see if my mechanical fuel pump is going bad? - Yahoo! Answers

 

[OVERKILL 19]

Replace the fuel filter first! cheap and if its not that your out $4 and you have a good filter now.

 

[dodgeguy]

Pump is a mechanical deal on the front of the motor (if is's a typical SBC)...unhook the feed line to the carb, unhook the HEI so it doesn't start...put a cup under the line and turn it over. There's a spec for how much fuel is pumped into the cup for how many seconds of cranking....

How would i check to see if my mechanical fuel pump is going bad? - Yahoo! Answers

Most excellent, although I did know it was mechanical....anything beyond that I was a bit clueless...LOL Thanks Dave!!

 

[OVERKILL 19]

truck ideling, grab a can of ether with a straw shoot a little aroung each vac hose, idel goes up U found your leak. take your time.

 

[dodgeguy]

Replace the fuel filter first! cheap and if its not that your out $4 and you have a good filter now.

Yep I am gonna replace that on Tuesday, just to help eliminate issues....Thanks!!!!

 

[Summitric]

Fuel supply problem........ Either fuel pump or power valve inside carb or fuel filter...... I know these carbs/engines like the back of my hand

had a few occasions where the fuel pump lobe on the camshaft was worn badly and wouldn't allow the fuel pump to pump properly... Lots of possiblilities, so you'll have to eliminate possilities.

Fuel filter first, then recomend fuel pump pressure test and also volume test.....

 

[dodgeguy]

Fuel supply problem........ Either fuel pump or power valve inside carb or fuel filter...... I know these carbs/engines like the back of my hand

had a few occasions where the fuel pump lobe on the camshaft was worn badly and wouldn't allow the fuel pump to pump properly... Lots of possiblilities, so you'll have to eliminate possilities.

Fuel filter first, then recomend fuel pump pressure test and also volume test.....

Yes doing it tomorrow morning at the shop....lol Gonna change the fuel filter first and take it for a spin...Truck has pretty low mileage (184700km) Then go from there..... :-D

 

[dodgeguy]

Thanks everyone for your input it is greatly appreciated!!!

 

[007sevens]

Fuel supply problem........ Either fuel pump or power valve inside carb or fuel filter...... I know these carbs/engines like the back of my hand

had a few occasions where the fuel pump lobe on the camshaft was worn badly and wouldn't allow the fuel pump to pump properly... Lots of possiblilities, so you'll have to eliminate possilities.

Fuel filter first, then recomend fuel pump pressure test and also volume test.....

I agree Ric rebuild the carb last after checking everything else. If you have a little cash Edelbrock makes a nice simple carb for these engines that works well. ut I would do as Riv has stated. A little birdie told me he knows his Sh!t.

 

[dodgeguy]

I agree Ric rebuild the carb last after checking everything else. If you have a little cash Edelbrock makes a nice simple carb for these engines that works well. ut I would do as Riv has stated. A little birdie told me he knows his Sh!t.

Yeah he might know a thing or two....lol

 

[dodgeguy]

ok soooo, someone along the way may have been even less enlightened on carbed vehicles....lol There was an inline filter {pre-filter?? hah}(which was ok but I replaced it anyways), and the filter that resides IN the front of the carb was probably 90% plugged (bulged really bad). Runs down the road nice now, no hesitation....took it up to a buck 40 and no problems. Carb is pretty damned filthy so gotta clean it (doing that this afternoon).

Question...is the little black valve in the carb FF a back flow preventer, a pressure regulator or what.....???

 

[GYMBRAT]

beaters can be fun

......and its been sooooo fn long since ive even looked at a non-fuel injected engine I couldnt even begin to help ya with ur question lol, sorry dg!

 

[Summitric]

ok soooo, someone along the way may have been even less enlightened on carbed vehicles....lol there was an inline filter {pre-filter?? Hah}(which was ok but i replaced it anyways), and the filter that resides in the front of the carb was probably 90% plugged (bulged really bad). Runs down the road nice now, no hesitation....took it up to a buck 40 and no problems. Carb is pretty damned filthy so gotta clean it (doing that this afternoon).

Question...is the little black valve in the carb ff a back flow preventer, a pressure regulator or what.....???

i would get rid of the inline filter, as the manual fuel pump on the right front of these engines isn't a very strong pump to begin with. Is the inline filter before the pump or between the pump and the carb.

The little black valve in the carb is a "rollover" valve or "backflow" preventer..... Most guys just take the spring out

 

[dodgeguy]

i would get rid of the inline filter, as the manual fuel pump on the right front of these engines isn't a very strong pump to begin with. Is the inline filter before the pump or between the pump and the carb.

The little black valve in the carb is a "rollover" valve or "backflow" preventer..... Most guys just take the spring out

Its between the pump and carb...I was thinking it would be a good idea to get rid of it, but the pressure was about the same with the FF and without, but if you recommend to remove it....

 

[dodgeguy]

beaters can be fun

......and its been sooooo fn long since ive even looked at a non-fuel injected engine I couldnt even begin to help ya with ur question lol, sorry dg!

hahaha, no worries the only thing I like carbed are my quads...the last carbed car I had was an '85 Aries Kcar, but I am a sucker for "Get this thing outta my yard..." deals!!