Fuel Pump 94 GMC Suburban 1500 350 V8?

Question

Hi have the above truck. I parked it and went to start no go. It turns over fine will not fire up. I noticed last few times I drove it it seem to hesitate a little. It has lots of fuel in tank no fuel going to electric carb. They call it fuel injection but looks like big electric carb. I poured a little fuel into carb and it fired right up and ran till out of fuel a second or two. I am thinking fuel pump if so where is it located and is a big job? Thank You Wayne

Answer 1

yeah I would have to agree, The pump is most likely in the tank. pump out the gas with a siphon pump, kind of tricky if you've never done it, you have to find a stiff hose to stick down the filler neck and push up and down hard to get the hose to push past the anti siphon door in the tank. then siphon away. I just replaced the pump in my tank on my 99 1/2 ton 4x4 burban last week as well. I had to have the quick release tools for the fuel supply and return lines, you cannot remove the lines if they are steel braided, without the quick release tools, be sure to get the kit with all different sizes in it. and make sure they are the plastic ones, the metal types are hard to sqeeze in the tight spaces. once you release the fuel lines from the pump you will have one electrical connector for the pump pressure sender, and one for the pump itself. The new pump that came for mine I got from autozone it cost $250 and it came with a new pigtail that had to be installed on the wiring side part of the truck, I had to cut the old pigtail off of the truck and splice in the 4 new wires, not that hard, but you will need heat shrink to keep moisture and corrosion out of the splices, as none came with the new pigtail. all that came with it were the splices. I used a floor jack to let the tank down slowly after slowly loosening the two long bolts that hold the tank straps up. Get a Chilton or Haynes repair manual $15 at autozone/napa. they have some good illustrations how to get the pump out of the tank. mine had a clamp that had to be pried out with a screw driver, then I had to use channel locks to grip the fuel pump and twist counter-clockwise while prying up on the plastic lock tab. Then the pump pops out, I tried to clean out the tank with clean rags, oh I forgot to mention, be sure to blow the top of the tank off with a air hose, especially around the old pump, before you take it out so no crap falls into the tank. Also you need to loosen the big rubber filler hose at the side of the truck, as well as the smaller rubber over flow hose. before lowering the tank. like i was saying i found it hard to wipe out the inside of the tank. I think I made matters worse, meaning it was actually cleaner before I attempted to clean it out. The new pump has to have a new strainer on the bottom installed, its a cotton filter. the pumps are spring loaded on three sides. you have to push the pump down and make sure it is centered exactly in the middle of the hole, of the tank, otherwise it will be canted, also you have to insert the pump at an angle in the opening because the fuel level arm sticks out away from the pump. push down and turn, I had to use a big flat head to keep pressure on it, while I pried the c-clamp spring back into place to hold the pump in position. then everything is installed in reverse order. make sure you install new hose clamps on the hoses. and you cant mix up the supply and return fuel lines because one is bigger than the other. you also have to install a new fuel filter make sure you buy one on the same receipt as the fuel pump, otherwise the warranty is voided if you do not install a new one. Have fun. It took me about 8 hours to do the whole ordeal.

Answer 2

I have the exact same problem only I allready changed the fuel pump a year ago! I found this on the web ;

chances are it is one of 3 things, a bad fuel pump relay: if it is, it costs about $15 and is located in the "under the hood" fuse box. Look under the fuse box lid for location of the relay. #2 The oil pump pressure switch/sending unit: you can determine this by unplugging the wire connector to the sending unit and jumping the 2 end terminals together it is a 3 wire connector. If the fuel pump starts which is identified by a hum from the tank then it is most likely the oil press/sending unit.#3 The wire connector to the fuel pump itself could also be bad, but this is difficult too because you have to drop the fuel tank to get to it also. I know the oil pressure switch/sending unit sounds unrelated but the wiring circuit to the fuel pump has a branch that is routed through the oil sending unit and it can cause the pump not to operate if it goes bad. The oil sending unit (OSU) is in a difficult location in the back of the engine under the distributor and it takes a deep socket to remove. The fuel pump, if it is actually bad, is a big job especially if you have a full tank of gas. It is usually best to remove the gas before trying to drop the fuel tank. Most tanks nowadays are difficult to get a siphon hose into. The fuel pump I bought cost $180 from an auto parts store and figure 2 or 3 hours of labor just depends on how good/quick they are. There are a few tricks to dropping the tank and there are some fuel line connector tools required but they are not expensive. If you do change the pump, you'll also need to change the fuel filter. After everything I said earlier, you may want to check that the fuel filter is not plugged up...it is a possibility, but I have never seen a plugged up fuel filter. I, of course, buy my gas at reputable places, but if you don't I guess it's reasonable to look at in addition to what I told you. Good Luck Hope this helps!

Answer 3

Wayne you may have determinded your problem.

The "big electric carburator" you mentioned is actually a fuel injector body. It sprays fuel into the intake and each cylinder will pull in what it needs to fire and run. Some automobiles use an injector for each cylinder. Yours only uses one injector. It is a good system.

However, before you go into replacing the expensive fuel pump, check the fuel filter and change it. When they plug up, the fuel can not get through. I believe it is under the truck on the frame.

If you have a little savy, unscrew the fuel line from the "big carburator", put the end in a suitable container. You will probably need a helper to do this. While holding the fuel line end in the container, turn the ignition switch on. Fuel should flow out of the fuel line. Be careful not to spill any down around and on the engine. If you have fuel to the "carburator" then either the "carburator" is stopped up or the electronics aren't telling it to "fire" and squirt gas down into the intake. There may also be a filter on the "carburator" to. I'm not sure about that. Check for it. It will be what the fuel line is screwed into.

If you have NO fuel coming from the fuel line and you have replaced the "on the frame filter", then you may think more about the fuel pump.

Before you change the fuel pump, check for 12 volts going to it. Also, on Fords and Chevys may have it. There is a collision switch the will turn the fuel off when you have a wreck. Sometimes this switch get bumped or jarred enough that it activates and shuts the fuel off. If it did the electric fuel pump would keep pumping fuel after the wreck and that would be disasterous. Check your owner's manual for this switch. You truck will NOT run if this switch is tripped. Good luck. Pops

Answer 4

It sure sounds like it is an inoperative electric fuel pump or something has opened up in the circuit for the fuel pump. You need proper diagnosis to be sure it is not an simple electrical problem first. These are in the fuel tank and it is a big messy job prone to rusty connections that lead to breaking other things when taken apart. You can't do much other than that.

Answer 5

I don't know if this is any help but I had a similar problem on an 86 olds. In my case I verified that I had a spark but no matter what it would not start. Further investigation led me to see that there was no fuel coming from the injector (throttle body in my case). I recall spraying a little starting fluid into the throttle body and sure enough it fired but I was getting no fuel. I tried a few things but in the end the problem was the dang ignition module. You see that module sent a signal to the computer that a spark was being produced and without that it would not deliver fuel. As far as an oil pressure sensor, that would make no sense to me because there is no oil pressure until the engine starts. I don't know what type of fuel delivery your engine has but if its throttle body you could try a shot of starting fluid to see if it fires, if it does then there is some reason its not firing the injector(s). If you have multiport that wouldn't work so good.

Answer 6

Had the same thing happen to my '97 at 120,000 miles. Pump is in the fuel tank. Need to drain the tank, drop it out of the truck to get at the tank top when the pump is mounted. About $600-700 at a shop. Bigger job, but not bad if you have a hoist.

Answer 7

either its the fuel pump, which is in the tank (big job) or its the fuel filter (not so big job) or it could be the dual injectors in the throttle body... what you are calling an electric carb. if th injectors are plugged up thn you will need to replace them. (medium job)

Answer 8

haha so many answers, it could be the fuel pump relay, ignition module(located in distributor) or the fuel pump itself

Answer 9

big job its in fuel tank

Answer 10

its in the gas tank on this one and yes its a big job,you,ll have to get some of the gas out of it,no -one can handle a gas tank with gas in it,it makes it to unstable to handle,and dangerous,i did one a week ago that was almost full ,had to get about all out of it to get the tank to the point that we could handle it when it comes down,good luck hope this helps.