1999 4.3 Jimmy Fuel Pump? 200k+ mileage.

76PATRIOT

MEMBER
1999 GMC JIMMY

Jimmy starts runs and will stall out off and on, will have trouble getting back home. Will start and idle OK, sometimes will run OK. Can't afford new fuel pump, hoping something else.

Fuel pressure will not come up with key on, start engine and it comes up to 55-60#s. Turn engine off, pressure drops instantly. Sometimes, not often, key on fuel pressure comes up to normal for maybe one second then drop to zero instantly. Cranking will start engine and then it runs. Difficult to diagnose.

Can't find the this specific pressure regulator or info about it on internet. Haynes manual says to take to expert, regulator is not on top of engine anywhere on this year and model. Since there are three lines that appear to go to tank, am thinking one line is vacuum and regulator is in the tank.

Any suggestions? Everything I read says it could be regulator (can't find it), plugged intank filter, poor pump flow, voltage, etc. Would like to narrow it down.

Also saw someone selling feul pump repair kit on eBay for $40 (electric pump, green internal strainer/filter, yellow external strainer/filter, inline hose & clear fuel hose). What is this all about?

1 Reply

CHEVY22

MECHANIC
1,375 POSTS

The regulator is under the upper intake on the rear of the poppett module very easy to get to, what bothers me is the key on pressure at all issue it should give 2 seconds of pressure and cut off, you may have a multiple issue, but losing pressure right away it most likely a regulator and if it is the fuel is either running down the inside of the upper intake or into the cylinders, you can also pinch off the return line easily and momentarily to see if pressure holds that way, let us know

jim