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73-87 Chevy _ GMC Trucks => Fuel Systems and Drivability => Topic started by: Cowman85 on April 10, 2009, 02:52:10 pm
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Hey guys just wondering what you would recommend for a elec fuel pump with a mild 350 with a 4bbl q jet?
there are a few available, just not sure if its worth spending the extra $40 to go from 97gph to 110-125gph?
The engine will be built at most to mild-mid performance within the next 2 years.
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For a mild 350 street vehicle the 97 gph will be plenty. The Carter pumps are very reliable, I've used several of them. The ones they call 8 psi seem to show about 6.5 psi on a gauge & work fine without a regulator. You want to mount it near the tank, the electric pumps like to push fuel, not suck it. Lorne
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thanks lorne!
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ok got one but it was not the one i wanted, i'm hoping to God that this is not too small.
its an inline pump with a filter too.
"posi flo" universal electric fuel pump
12v, 4-7psi, 32 gph, 120Lph, eliminated vapor lock, self priming.
will this be sufficient for my 3/4 ton 2wd 35ci 4bbl?
i've already installed it, its pretty noisy too, i've filled the line going to the tank with gas hooked it back up and tried starting and nothing, it doesnt seem to be pumping anything.
aside from taking the line off from the carb and filling it full of gas is there another way to get this thing going?
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You don't really need to prime an electric pump. Are you sure you have it installed correctly (inlet-from tank, outlet-to carb)? Could you have it installed in the return line? Why did you decide to install the electric pump? Lorne
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to go with what Lorne said did you use the bigger line out of the tank?
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i used the 3/8 line which is the biggest line i believe (same lines that were hooked up before)
i'm pretty sure i installed correctly, kept the flow in mind etc, i will check again though.
i heard that these pumps only like to push not pull so getting the fuel back into the line from the tank is required for a weak pump, you guys have any thoughts on that?
i installed this one because it was only $80 and i'm flat broke right now, skipped a new cam because i dont want something else to go in the engine if i wake it up, then i really wouldnt be able to afford to fix it. I was waiting to do a rebuild to replace the internals etc.
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try taking it out and testing it in a bucket"not submerged" but put a fuel line on her and see if its pumping if it does double check the lines
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i should be able to test it this afternoon.
so straight up this pump should be enough to pull the fuel right out of the tank even with the air in the line right now?
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well i did the test on the pump and it worked well,
jerry can(in line) and filter/pump in the middle and then dropped the other line into a clear glass jar, all went well.
so after the test (ran for 5 min) i took the lines off (trying to keep as much gas inline as possible) and hooked everything back up.
started great and ran great, for a couple of minutes, while putting my tools away it started to die down (i noticed because i just adjusted the idle screw again), then just died, i tried to start it again and nothing, but i could tell from the sound of the pump that there was no fuel in it again.
so this pump is not capable of pulling the fuel from the dual tank setup?
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Sounds like you've got it plumbed in the wrong spot. Do you have it attached to the outlet on the switching valve, because that's where it needs to be.
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its the middle line from the switching valve, the same one i ran for the test is the same that is always used.
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I didn't see where you answered my question as to "Why did you change to the electric pump?" Without knowing what went on, you/we may overlook the real problem. Lorne
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sorry lorne didnt mean to, I was having problems stalling and not starting when i first got this truck. I changed out the filters, pump (double checked the spring), spray cleaned the carb, changes lines, i ended up running it out of a jerry can for awhile lol. I ended up getting it towed to a mechanic recommended by a friend of a friend, he diagnosed it as being the fuel pump lobe off the cam. Right now i am a student at nait so i am on a strict budget, i would rather of replaced the cam but i didnt want to wake the engine up if there were anymore problems. We decided to bypass the problem: electric fuel pump, block off for the old one.
With that all done, he found me a used one (posted in another link) and away i went. Well that pump crapped out a week or so later, knowing that i dont want a doorknob working on my truck i needed to fix this myself. So i went shopping for pumps, i could only find 2 different types, the same large type that was on the truck for 200(holley blue 120gph) at JB's or an 80 small inline at napa(posi flo 32gph). So i told the guy at napa what i had, how much line etc, and asked him if this would be sufficient for my application, he said yes we recommend it for half tons usually. I figured that was good enough as i wanted better gas mileage and dont care to speed much anymore, i went with it, here i am now...
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i called jb's again and a different guy told me they had a holley 97gph for 150, might get that in the end but will have to toss couch for change lol
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Ok, I hadn't noticed you were the "Flat cam lobe kid" :D Here is my interest in the reason...Could the "Bad fuel pump, cam lobe, ect." have been mis- diagnosed for the very same problem you are having? Where did you have you rigged can installed? Before the switching valve, After, right before the fuel pump, just out of the tank? I feel you should get on the hose comming out of a tank & put your pump on there (by-pass all of the Two tank switching crap with a section of rubber hose) & connect it to the steel line coming up the frame (at the back of the cab), take the line off at the carb & try, if this doesn't get fuel to there, put on your rig can before the pump & try again. If this gets you fuel...drop the tank, there will be where your problem is. If it doesn't get you fuel, I would be suspect of a hose/line kinked/plugged. Once you have fuel to the carb, I would try installing the mechanical fuel pump...it will most likely work. ;) Lorne
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lol flat cam lobe kid, got a nice ring to it.
I put the pump just under a foot away from the switching valve, as close to the tank as i can get with this pump.
When i got the precious pump put on i had installed a larger gas tank on the passenger side as well, so i know the tank is good.
The test i did with the jerry can tells me that there is just too much line for that little pump to pull, i tried both tanks as the passengers side is a few feet closer to the pump.
It is a small pump and thats what i was afraid of, the guy at napa just didnt fully understand my application i guess.
"put on your rig can before the pump & try again" what did you mean by rig can?
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I am beginning to wonder if you have a problem with your pickup tube. The pumps shouldnt run dry because the engine used to much fuel. It almost sounds like its sucking air either at or before the switching valve or the pickup tube.
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so you think that the pump is enough to run it no problem?
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"The rig can" was just another name for your "jerry can". It would seem unlikely that both sides would act the same if the problem is at the tanks, however one think to be aware of...It is easy to end up with a kinked shut supply hose coming right out of the sending unit. If the hose is not routed carefully or if the hose was made a little long to aid in hooking it up, this can happen...ask me how I know, on second thought, don't ;) My plan would be the same as earlier. Get back near the tank & put in your pump (by-pass the switching valve) straight to the steel supply line going to the front & try it. If it doesn't run...Put the "in" side of the pump in your "jerry can" & repeat. Good Luck, you'll get it figured out, Lorne
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go figure never heard them called a rig can before.
since the truck was running fine before when the previous electric fuel pump was on i am leaning toward this pump being to small. It is only the size of a computer mouse.
i could see it pulling off just the one tank like you suggest but i need the second tank for out of town trips so it wouldnt work out in the end for me, i think i will go guy the 97gph holley and hook that up, besides there is no way the new pump will make more noise than this little firecracker!
but when i'm down there i will check it all out anyways, thanks for the help :)
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Ok, I went back & read your other post about the whole fuel pump, cam lobe, rip-off guy, ect. A few things of question. So you/he removed the fuel pump that he put on after the dispute over the cost, Is this correct? The truck ran correctly while this pump was in place, correct? Where was this pump mounted & what all has been changed, R&I'd, ect. since that time? Are you saying you are trying to suck from both fuel tanks at the same time? I would like to see you try the one tank/jerry can as a diagnoses to your problem, once that is figured out, you can hook up both tanks if you like, but it needs to be through a known good switching valve. You mentioned money is a little tight, testing to be sure your buying the part you need costs little/nothing...I suggest you do a little more figuring, even a little pump should have enough umpha to run the engine at idle sitting still unless your "lift" is too severe.
I put the pump just under a foot away from the switching valve, as close to the tank as i can get with this pump.
Was the pump before (on the tank side) the switching valve or after (between the valve & the carb)? Was the valve by-passed while you did this?
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the only things changed are the fuel pump and a new tank on the passengers side, the pump was removed. The switch valve has always worked fine.
The pump was in the same place as the new one, and everything was running fine before the pump was removed, thats why i think the pump is not strong enough for this place in the line. I will be testing to make sure though, i dont want to spend the money if i dont have to.
I just cant see that pump pulling all the way through the valve etc, thats why i was skkeptical of it to begin with, there is also a bit of a long loop of hose near the valve to make it easier to test for now.
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alright, the new holley pump (97pgh 7psi) has done the job, bolted in and hooked up the truck started no problem and runs great.
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Great, glad you got it. ;D
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I woulda thought the other pump woulda worked ok, that's a little weird. But yeah, glad you got it worked out.
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thanks for the help guys its appreciated :)
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Good Deal! Glad to see you beat it.