83 Vandura 2500 - area on pedal with limited throttle?

[candersonosu]

I just purchased an 83 Vandura. I searched, but couldn't find much about my problem. At first, I thought the engine was hesitating / not getting fuel. When driving it seems to lose all / most acceleration at times. Sometimes rapidly moving the pedal gives it acceleration again, but other times nothing. After driving it several times, I now feel that maybe the problem is a certain portion when depressing the pedal is causing limited response to the throttle. It seems that when the problem occurs, it stops when I almost floor it. I did replace the fuel filter. Anyone have any ideas? Thanks in advance!

 

[1987 GMC Jimmy]

Will it idle okay most of the time, especially when warm. I'd check the accelerator pump on it. With the engine off, pull the air cleaner and look down into the carb. Move the throttle from 0 to WOT and see if you can see two healthy squirts of fuel begin as soon as you move the throttle. If they're weak or one or both are missing, it may be a bad accelerator pump diaphragm or just a gummed up carb. What kind of carb is on it, and has the van sat for any extensive period of time recently?

 

[Honky Kong jr]

Will it idle okay most of the time, especially when warm. I'd check the accelerator pump on it. With the engine off, pull the air cleaner and look down into the carb. Move the throttle from 0 to WOT and see if you can see two healthy squirts of fuel begin as soon as you move the throttle. If they're weak or one or both are missing, it may be a bad accelerator pump diaphragm or just a gummed up carb. What kind of carb is on it, and has the van sat for any extensive period of time recently?

Way easier in a van pull the dog box and air cleaner it's right there..

 

[1987 GMC Jimmy]

Definitely. If it's anything else, I can't be so sure. If it's anything like working on a motorhome, anyways. That can get ugly.

 

[candersonosu]

Was away on vacation, but got back and looked at it today. Previously it was sitting, for months on end without being started. I checked the accelerator pump, and I see two good jets of fuel. I tinkered with it for a while and after driving it, it only had the issues once when I was first driving. Maybe I just need to get it on the road and run the carbon and crap through it...

 

[1987 GMC Jimmy]

duplicate post

 

[1987 GMC Jimmy]

That's good on the carb. Maybe it's having an issue with water in the fuel from being exposed to moisture/precipitation while sitting up. I'd go to Walmart and get a bottle of Heet to put in it. Very cheap. One bottle treats 20 gallons, I believe. Do you know how many miles the motor has? It shouldn't have excessive carbon buildup unless it was ran overly rich due to bad ignition parts or carb tuning or if it was driven excessively in short little bursts that didn't allow it to warm up to operating temp.

 

[candersonosu]

You may have been correct with water in the fuel / bad gas. I added some fresh fuel, plus a can of seafoam. Now the problem seems to be gone for the most part. Thanks for all the help guys!