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Can anyone help? Fuel prob. still..

Discussion in '1973-1991 K5 Blazer | Truck | Suburban' started by Emmettology 101, Aug 17, 2000.

  1. Emmettology 101

    Emmettology 101 3/4 ton status

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    Hello,

    Ok, If you didn't know my past problem I will retell the story and I am still getting some of the problem.

    I put in a 1990 350 in my 82 JImmy. This engine has the new style heads and no provision for a mech. fuel pump. So I went out and bought a cheapo Auto Zone in line pump. Put it in up by the engine and I got a bog and stall going down the road.
    So I then moved the pump to the rear where the frame make the final bend before it straightens out and goes forward. After I moved it back there it wouldn't pump fuel. So I went out ot Summit and bought a Holley "red" pump, it wouldn't pump either.

    So after all I replaced all of this with new:
    Carb
    Intake
    Fuel line(from tank to carb)
    Fuel filters
    2 different pumps

    I finally got the cheap pump to push fuel once I aided by siphoning. So it was pumping good, but still had a bog. So I went out and bought a pressure regulator that Holley told me to run at 4psi. i installed it on the firewall similar to what "Trcuks" did to the Willys. I never set it and it came pre-set at 2.7psi. i thought I would try it and see. Well the bog went away a little but is still there some.

    The only things that aren't new in the fuel system are the tank and sending unit.

    I get the bog if I am sitting there idling and then pull off the side of the road and pull away it will bog some(but not all the time) and then when I come to a hill and have it at a medium throttle and then roll into it to get up the hill and it bogs.

    I tried blowing air into the fuel line and into the tank to try and free some tuff fromt he baggy filter in the tank and now my gauge is off. Could I have hurt the sending unit doing this?

    Where am I going wrong?

    I took the Holley pump back and got my money for it and the cheap pump is a Masters pump and is rated at 5.5 - 9 psi.

    The fuel line is 3/8" and is mostly metal except in a few spots. I am running new filters, one before and after the pump and i took the screen filter out of the carb.

    Any suggestions???

    Mike
    1982 GMC Jimmy - <font color=green>Emmett</font color=green>
    http://emmett.coloradok5.com
     
  2. White Knight

    White Knight 1/2 ton status

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    Thers about 4 lines down there and don't take this wrong . But did you hook up on the line to carb or return to the tank?, and check for any air in lines, like a small pin hole before the pump, any air in there and the electrical pump gets pyscho..

    White Knight
     
  3. Emmettology 101

    Emmettology 101 3/4 ton status

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    I wouldn't take it the wrong way. I followed the line all the back to the tank and it looked to be the main line. The return line I have blocked off since I haven't been using it for the past 5 years.(blocked off up line, not at the tank)
    The whole fuel line from the tank output to the carb is all brand new and shows no signs of leakage..

    I am going to pull the tank in the near future and see if I see any problems. I am debating on going with a fuel cell, but I would have filling problems. I do want to replace the tank anyhow since I got a big dent in it the last time I was out wheelin.

    The main ine is 3/8"'s and the rest are all smaller, correct? Actually when I look up under there i see a vent, a line going up to the gas cap, a smaller return line and a main line. I have it hooked to the largest line.

    The only things I can think of are either:
    tank has a leak?
    Output line has a leak before new line
    baggy in tank is plugged
    Sending unit is bad

    Other than these I am stumped!


    Mike
    1982 GMC Jimmy - <font color=green>Emmett</font color=green>
    http://emmett.coloradok5.com
     
  4. Shawn

    Shawn 1/2 ton status Premium Member Author

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    I'm not sure what pump you have but I've tried one of those cheap pumps that look like a box or something. It couldn't keep up with the volume of my 454. I returned it and bought a Carter which works great now. I'd suggest running a fuel pressure gauge and see what it does when you drive it.

    BTW- I have an Autometer fuel pressure gauge for sale if anyone is interested. It's 0-10psi and it IS mechanical which means you CAN'T mount it inside the vehicle for safety reasons. I was going to buy a gauge cup and mount it on my hood but then I bought FI which requires a high pressure gauge.



    Shawn
    87 K5
    few mods
     
  5. White Knight

    White Knight 1/2 ton status

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    When you hooked up the fuel pump in line, did gas readily spill out the line you where on? at least from the tank side?

    White Knight
     
  6. BUDDY

    BUDDY 1/2 ton status

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    Sounds to me like you have too many filters. I read in one of my magazines, (I think it was HOT ROD), an article about quadrajets and JET performance was the reference they used. The guy from Jet said that he keep the in carb filter and that's it, any other filter just added restriction. Maybe you could call them or e-mail them or some thing, see what they say.

    JET Performance Products
    17491 Apex Circle
    Huntington Beach, CA 92647
    Voice: 714-848-5515
    Fax: 714-847-6290
    Email: Sales@JetChip.com

    Hope this helps,

    Buddy

    I've got my dream truck and it's a 72 K-5 that is getting there!!
     
  7. 82K5

    82K5 1/2 ton status

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    i also had a fuel problem, but it is fixed. have you checked the pump rod in your motor? it runs off of your crankshaft? i trashed the in carb filter and only run an inline glass purolater filter with changeable elements, 3/8". mechanical pump should get you about 7lbs. pressure. my 82 runs a pump with 3 lines. i did replace everything and i finally pulled the tank and it was full of very fine, powdery rust. a new steel one ran me $120. that was what was clogging my stuff up. so now i got a new pump, tank, and carb.

    Phil in K.C.
     
  8. Can Can

    Can Can Pusher Man Staff Member Super Moderator

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    I run a Carter two-stage electric pump back by the fuel tank, and use an-inline filter BEFORE the pump as well as the carb filter. I've done so for over five years and have never experienced fuel starvation. A mechanic friend said that the inline is a good idea because it really helps prolong the life of the pump.........
     
  9. 82K5

    82K5 1/2 ton status

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    just reread your post. you said you are running an inline pump. you didn't say if it was mechanical or electrical, although i have never seen an inline mech. pump. if your motor doesn't have a place for a mechanical pump than it should be running an electrical one. also if it's a '90 motor you should be running fuel injection. if you have FI you need a high pressure pump. 7-10 lbs. isn't going to work. high pressure pumps run about 20+ lbs?
    got to be the pump. or the tank. or.......it's a blazer. good luck. i know mine kicked my ass the first 6 months.

    Phil in K.C.
     
  10. Shawn

    Shawn 1/2 ton status Premium Member Author

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    Phil-
    I'm pretty sure he's running a carb and not FI. Just the block and heads are from a 90.

    Shawn
    87 K5
    few mods
     
  11. 82K5

    82K5 1/2 ton status

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    yea i figured that too. but he didn't say exactly, or did he. try the tank, then pull your hair out if that's not it.

    Phil
     
  12. Emmettology 101

    Emmettology 101 3/4 ton status

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    Originally yes, but then I replaced the whole fuel so then it did not, but I primed it to get the fuel flowing.

    Mike
    1982 GMC Jimmy - <font color=green>Emmett</font color=green>
    http://emmett.coloradok5.com
     
  13. Emmettology 101

    Emmettology 101 3/4 ton status

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    Yes just the block and the heads are from a 90. I am using a Performer intake for the newer heads and an Auto Zone Qjet.

    The pump is an elec. inline Masters pump from the Zone also. I had a Holley but it didn't pump anything.

    Mike
    1982 GMC Jimmy - <font color=green>Emmett</font color=green>
    http://emmett.coloradok5.com
     
  14. i_4x4

    i_4x4 1/2 ton status

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    I have the same Problem on my '85. Sometimes it works great & other times it bogs. I'm running an electric pump by the tank w/ the mech. pump after. I get 4 psi w/ just the electric, & 7.5 psi combined w/ both. Just frustrating isn't it.

    i_4x4

    LET'S ROCK
    Don't follow me you will get STUCK!!
     
  15. mudfanatic

    mudfanatic 1/2 ton status

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    I just read everything, You are running an electric pump close to the tank with a filter before and after.
    1)The filters are fine no problem there.
    you plugged the return line!!! this is ok with a mechanical pump but not with an electric pump.
    2)A friend of mine had this problem with a car that he swapped engines on and we finally discovered that when we opened the return line to the atmosphere and let the tank breathe his performance went back to normal.
    Dan

    <font color=red>get involved with land issues or lose the land</font color=red>
     
  16. dumbfounded

    dumbfounded 1/2 ton status

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    The tank should "breath" through the gas cap. Try replacing that. The carb can also get too much fuel pressure. The float valve will leak by and will fill the bowl then can get into the engine and "choke" it till it clears. Try the pressure gage. If you get a mechanical one you need an isolator if you want to put the gauge in the cab. It would be nice to see what the fuel pressure is doing. The 90 block should still have a place for the mechanical fuel pump, it should just have a cover over it. I've got a fuel injected block and there is a simple bolt on cover over it. Take it off bolt up the fuel pump and it should work. I believe either too much pressure or something on the inlet to the pump. It may be working too hard to suck the fuel. Also check to see if the fuel line is passing by anything very hot. You could also have minor vapor lock. If a fuel line passes near the exhaust you can actually be boiling the fuel inside the line turning it into vapor hense vapor lock. Also check for vacuum leaks around the carb or tubing.

    Love, Peace, and Hair Grease...........
     
  17. getsome

    getsome 1/2 ton status

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    I think that you should start looking at the simple things. The first thing that i'd do is unhook the fuel line going to the carb from your fuel pump and turn the ignition on just to see if your getting gas out the other side of the pump. If your not I would drop the tank, pull the sender out and replace it. I think that you said that you shot some air into the fuel line going back to the tank. The only bad thing that can happen from this is that you might have blown the "sock" off the pickup tube. If you are getting good fuel out the other side of the pump I'd hook the line back up and take it off again at the carb and repeat the test again. I had a problem like this on my CJ7 but it would die after 200 feet and it was a leak on my Carter pump at the top where their is a gasket. I figured this out by a friend seeing air in my fuel filter befor it went into the carb.(I had a glass fuel filter) I have a cheap Auto Zone pulse type inline electric fuel pump now in my 84 with a 350, preformer intake, and Edelbrock 600 carb and it works fine but is anoying. I would just start at the back and work your way forward. Let me know what you find.

    Getsome
     
  18. Thunder

    Thunder 3/4 ton status

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    Have you had this problem ever sence firing up the new engine? Because it sounds to me like a accelerator pump or jetting problem to me. If it was a fuel delivery(pump)problem you would loose power under hard acceleration or high speed.Not usually a bog off idle. Also the float level may be wrong. Sometimes with after market performance intake manifolds it takes a bigger jets to keep the manifold wet with fuel.Because the passages and ports are bigger, If the manifold dries at idle you get a bog. Try bigger jets.
     
  19. sosamantx

    sosamantx 1/2 ton status

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    Try this, I would get a gas can with some gas in it and get some fuel line (probably like 2-3 feet), hook up the fuel line to the pump and shove the other end into the gas can wound around so that the opening is on the bottom of the tank. Now see if your pump is working, and check it at various stages (downstream, towards the carb). If it is, then the problem is in the tank. If not then look elsewhere. Look I have started several cars this way and ran them like that during the break in period. The only difference is that I had a mechanical fuel pump. And by the way, I currently have 3 fuel filters on my 74 Nova. I did have 2 fuel pumps on the Nova (mechanical, and a electric w/switch, as an aid), now I took off the mechanical and bypassed it. I have a Carter fuelpump as well, on my sb350 and it is enough for my Holley 650 double pumper. I was told that the pump would not be big enough. I only have that many filter because my car is a 74 and the gas tank is rusted out and it kept on getting trash between the needle and seat, causing it to flood out. I did have 2 filters but trash got past them. - Steve
    Oh and Fyi, Holley carbs like 6-7 psi, not sure what you have though. Oh and what about the float level, if it is adjustable.

    Steve Sosa a.k.a. "sosaman"
    http://sosaman.home.texas.net/carpics.html
     
  20. Emmettology 101

    Emmettology 101 3/4 ton status

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    Sosa - I am running a Qjet with a filter before the pump and one up by the carb. I have taken the line off before the carb and the fuel shots ouot, but I haven't tried running a totally seperate tank yet.

    Mike
    1982 GMC Jimmy - <font color=green>Emmett</font color=green>
    http://emmett.coloradok5.com
     

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