86 blazer 4X4 fuel pump issues
 

Hello, Ive got an 86' blazer 4X4 with a 2.8 V6, which is only used to launch boats in the yard. I tried to start it the other day, and it cranks fine but wont run unless fuel is poured down the carb. Ive got a half tank of new gas, (guage works fine) I can put 12vdc on the small wire by the fuel pump relay and the you can hear the pump running in the tank, but no fuel comes out of the fuel line to the carb. (It has throttle body injection.) My question is, If the pump is running, could it still be bad/ Is it a common failure for the pick up tube to fall off, or is there some other issue. Im contemplating cutting a hole in the floor to access the fuel pump, but thought someone may have a simple thing I could check before getting extreme. Thanks in advance.

When is the last time you changed the fuel filter? It's the first thing I would check. It's located on the inside of the frame about the middle of the driver's side door. 16mm and 20mm wrenches will hook you up. You only need about 13 psi (if I remember correctly) and it doesn't sound like you're getting it at the TBI.

actually the fuel filter is located in the engine bay behind and underneath the power steering pump.

The fuel filter is located beneath the power steering pump. I removed the fuel line from the carb and Im getting no fuel at all. I can hear the pump running in the tank, and i was wondering if there was some sort of solenoid valave for the fuel, or if the pick up had fallen off the pump, or if the pump was possibly failed. Im not really fond of draining and dropping the tank, if necessary i will just cut a hole in the floor to acess the pump. Thanks for your responses!

its possible the relay is bad. When is the last time the filter was changed? is the fuel pump original? Im not sure if there is a solenoid, Im pretty sure its just the relay for the pump. I would start with the filter and if that doesnt fix it, then try the relay, and if that doesnt work, the pump would be next.

I bought the blazer just for pulling boats around the yard and launching them. It isnt road worthy because the previous owner couldnt keep the front end aligned and was tired of dumping money into it. The carb isnt getting any fuel to the throttle body at all( the fuel line has been removed to check) The filter is located bhind the power steering pump, and has never been changed, i would doubt seriously that it is completetly clogged, as there no fuel at all coming from the fuel line to the carb. My question is, Can the fuel pumps in these blazers be failed if you can here it running in the tank? It would be great to hear from someone who has actually changed a fuel pump in the tank and can verify the setup. A few of my redneck freinds have suggested using an outboard fuel hose to see if the line will prime with fuel, from the tank, and they suggested an inline pump to eliminate the need to drop the tank(which is 3/4 full of fuel) Im just not sure which type of pump to buy, due to conflicting fuel pressure requirements- im hearing 13 psi and 35 psi to pressureize the throttle body. Thanks in advance guys!

Is your truck TBI or is it the stupid feed back carb? Pressure requirements for the TBI engine is 9-13psi.

And I have definitely seen a fuel filter stopped up enough to not get any fuel through it. Especially if it has never been changed since '86. I would want to change the filter before going through the trouble of pulling the tank. that will likely be a pretty lengthy project.

I have replaced quite a few in tank fuel pumps. You won't get good flow if you are trying to pull it through the old pump. I would suggest you verify the fuel pressure out of the pump before even thinking about replacing it.

Im thinking its got the TBI, but it has 2 metal fuel lines going to it. Could you describe the feedback carb to me? thanks!

You should have the TBI engine in your truck, but my references still detail the old Rochester E2SE carb. Provided you have the TBI engine, the throttle body should have two pods that extend up over each of the bores through the throttle body. If that doesn't describe what the top of your throttle body looks like, then you have the older carb setup.

But from your description of having two lines running to the throttle body, it sounds like you have the TBI engine. There isn't a return line on the carb setup.

You said on your original post you have TBI. Yes psi should be 9 - 13. I would definately check/change the filter and you might even give the pump a start while you have the line off. I'll bet in 25 years it has accumulated a lot of garbage especially with the filter not being changed. I have dropped a few S10 tanks (present 94 twice) and if the pump is running and you hear it like you say then you have blockage somewhere. The pump would have to come off inside the tank and that's highly unlikely given how it's put on. If you pull it you'll see what I mean. If you do remove the pump make sure you replace the strainer attached to the bottom. Actually I can hardly believe it's lasted 25 years. I'm not a fan of cutting holes to access the pump/sender. I don't think the tank is that hard to pull. Just remove the left rear wheel and it makes getting to the lines a lot easier.
I think if you just disconnect the fuel line upstream of the filter you'll immediately see the problem.

there is no silonoid on the pump i just got done changing mine and if the pump is kicking on then its not a relay but if you don't beleive me you can just switch relays they should be both atatched to a metal braket under the hood infront of the driver side one is for fuel and one is for the air so switch them over and try that but i don't think thats your problem. if the pump is working then its probably something else disconnect the fuel line off the fuel filter coming from the pump turn key on and see if gas come out if it does i would think it has something to do with spark and not fuel maybe a new cap and router will do you good

Only problem is he said he doesn't have any gas coming out with pump running and the line at the TBI off.

im putting money on a clogged fuel filter.

Me too. Or at least garbage in the line. But I'll take the filter too. Man it's only a couple of minutes to remove the line.

if it were me, I would change the fuel filter. In the process though, while I have the filter disconnected, I would put a jumper to the pigtail wire hanging off the fuel pump relay and see if fuel comes out the line where it attaches to the filter. If gas comes out, youve found your problem area.

I have changed the fuel pump on an 89' with that TBI system. The pumps usually outright fail on these and won't run at all when they stop producing noise to hear. So I would say the easiest way is to take the fuel filter off and see if gas comes out when you do that, otherwise if you think its a real PITA to do that. Just take a copper rotating cutter and cut the line off on each side of the fuel filter. Buy a new filter with two new ends and some rubber fuel line withe clamps. Total project will take you twenty minutes and probably twenty bucks.

Well, guys i bought a new fuel filter and began my attem pt to install it after work at 4pm. (BTW Ive worked on Cummins for over 15 yrs and have had chevy small blocks since I was a kid) But this little endaevor wasnt pleasent. I was thinking i could simply drop the filter and have it done in 10 minutes. But NOOOO. First After removing the grimy filthy power steering pump, i began the chore of removing the 8mm bolt that holds the inline fuel filter in place while being devoured by sand gnats. But im not complaining. I get the filter out, and I can easily blow air through it. So I know its not clogged. Now I do a test, and apply 12vdc to the little pigtail next to the fuel pump relay, and i can hear the fuel pump running in the tank, but no fuel is coming out of the fuel line- at all. At this point, i take out a razor knife and cut a hole in the fabric in the back over the fuel pump location, because tommorrow, Im going to saw a big hole in the back of it to acess the pump. There no way in hell im dropping the fuel tank, and if it fails again, I will have a big hole to access the problem area. I install the fuel filter and notice the fuel supply line is steel on on end and rubber fuel line on the other, so this way GM can gouge you for that "special fuel line" at the dealer, if your fuel hose ever ruptures. The return line is the same way. After installin the filter, i begin th mundane chore of tightening the 8mm bolt that holds in the fuel filter, and is purposely pointing towards the rear of the car, to ensure the task is slow and ardous. I then install the power steering pump, just 3 bolts and tighten the bolts and belt. One part I ddint mention earlier is when i used a pair of channel locks and an axe to remove the AC compressor and hoses. it was in the way, anyway. Its at this point im reminded of why i drive a toyota. I opened the hood to my toyota and grabbed the fuel filter and and removed both clamps with a pair of pliers and removed it in less than 10 seconds, without getting any grease on me. Then for ****s and giggles, i held my breath, and reinstalled the filter on my toyota, then shut the hood, and started it, and then exhaled. I craked the top on a busch beer and thought about how i was going to saw open the rear of the blazer to create an acces panel- that should have been put there by the engineers at GM. Taking something simple, and making it hard, a sad fact with american cars nowdays. Tomorrow the fuel pump will go down, and the blaz4er will be moving boats around the yard again. Im starting to understand why the previous owner sold this thing to me for $400 cash. Its got 1 tire that goes flat after about 8 hours, and everyone says i should repair it, but no, its my anti theft system. after using it in the yard, the tire goes flat by the end of the day, and it ensure none of the neighborhood punks will take it for a joy ride. Then i would have to buy another 4x4 for abuseing in the boat yard. they tried to stel it once, and ripped out the stupid alarm system, but it would run for them, lol. I also really love how the fuse panel is hidden way up iside the drivers side firewall behind the brakepedal area, really difficult to access. everything seems difficult on this thing, compared to other vehicle Ive owned.

So I get up early, mark the corners and cut myself an acess panel. I remove the grit and debris from the pump/float assembly and remove the sealing ring to gain acess to the pump. Note picture 12--- the pump is working fine, but the short rubber connection tube has a hole blown through it. At first I think of replacing the pump with the new one i bought, but noticed several variations witht he replacement pump, so I just changed the rubber tube and clamps and reintalled the pump/float assembly. I remember when i was young, I had a 69 Chevelle, and when the feul pump failed, I just had to remove 2 small bolts from the front of the engine to replace the pump. None of this crazyness with an electric motor running inside of your gas tank. Aftr finishing, i turned the key on, waited about 30 secondes for the pump to prime the fuel system and it started on the first try. The inside of the gas tank looked great, the lines are all clear, and the filter was ok. so for everyones notes, if you hear the pump running inthe tank, and youre getting no fuel, at all- its probably the little crappy rubber jumper tube has ruptured- possibly due to the alcohol they are adding to the fuel we use nowdays. Thanks for your inputs, guys!

The picture with the brake master cylinder, shows the location of the fuel filter, hidden benath the power steering pump, and right next to the exhaust manifold. Really diffult to acess.

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i just dropped the tank in my '87 and the tube could have fell off but your relay could be bad.I'm in the same boat your in.