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Engine cutting out

Discussion in 'Chevy Trucks' started by Spence, Jan 19, 2001.

  1. Spence

    Spence Junior Member
    Messages: 13

    I have a 83' Chevy Silverado K10 with a rebuilt 350. It has started cutting out when driving down the road, sometimes for a few seconds. It completely loses power for a few seconds, comes back, loses it again, and so on. It doesn't do it while its changing gears, its when you are cruising. (not while using cruise control, just driving.)It did this once before when the intake was leaking, but its not leaking. I just had a new carb. installed and I thought that was the problem, but its not. The carb. did need replacing anyway. What would be causing this? I was thinking that it may be the fuel pump. Or am I wrong?
     
  2. 4x4k20

    4x4k20 Member
    Messages: 72

    it sounds like your rite replace the fuel pump it dosent cost much just a pain in the a?? to replace.but it aint that bad
     
  3. 85w/350

    85w/350 Senior Member
    Messages: 190

    most likely the fuel pump and like 4x4k20 said fuel pumps are really cheap anywheres you look to buy one...just use caution when losening the fuel line not to break it...also I hope that you have a metal fuel line. I broke my fuel line already trying to wiggle it lose and they dont sell prebent new lines so I figured rubber hose would work well...it did until I'd take like 2hr trips when the engine would get warm the fuel in the rubber hose would evaporate before it reached the carb and it would cause dry lock and kill out...sounds kinda like what you are experiencing...so I bought a new metal fuel line and I borrowed a pipe bending tool and made my own new one...it is a pain if you need to pull the fuel line its worth taking the alternator out. Oh yeah while i am telling you what not to do...when pulling the fuel pump be sure and notate which bolt comes from which hole in the block, one bolt is slightly longer than the other if you mix them up you might notice a nice oil leak ;)
     
  4. linky

    linky Junior Member
    Messages: 3

    spence
    Prior to landscaping i was an auto tech. for eleven years.It sounds like a fuel delivery problem. What was the original problem? Why replace the carb. and not have it rebuilt? TEST-if you start from a stop full throttle through the gears does it die down and pick back up after several seconds?[in doing this you are trying to use up the fuel-if you the fuel is not being replenished fast enough the engine will start to die down and pick back up when the fuel bowl refills]if this is the case i would suspect the [floats are out of adjustment] restricted fuel filter or low fuel psi.Personaly i think the float level is set too low.I think your fuel psi should be between 6-9 psi.You can check fuel psi by buying a cheap gage and a piece of rubber hose.connect the gage to the fuel supply line and crank engine for several seconds.Watch the gage it should read 6-9 psi while cranking if not replace fuel pump.Or you can connect a hose to the fuel line and hold it into a clear container have someone crank the engine it should shoot a stream as big as the hose and pump 6 oz. of gas in about 5-7 seconds [about] a coke bottle works well for this.I would call the shop that performed the work and tell them the problem.The fuel filter SHUOLD have been replaced with the carb.I hope that i was of help to you.It's difficult to diagnose a problem over the pc. If you have any more questions or the fix email me.
     
  5. Power mad

    Power mad Member
    from Oregon
    Messages: 75

    I've had that same problem on a few different rigs. One was a fuel problem, the other times it was electrical. And it turned out to be the coil(hei) would be going down the road and it would start to cut out, let off the throttle and it would smooth out eventualy It got so bad that I had to tow it home. went through the fuel system and it all checked out, pulled the cover off of the coil and it was oviusly shorted out. Melted right through the cap and into the rotor. Put in an Accel super coil, cap, rotor and it drove fine for a few days. Then the same thing again, only this time it was the copper button under the coil to the rotor that fried, did it twice more. still waiting for a third time. got extra button in glove box now. Just haven't figured out why it keeps doing this. Had the module checked and it was OK, have good power source, good ground. Was told that the super coil was too hot, but I have had many of these and have had no problems. And it seems to me that this problem started before the addition of the coil. Sorry I'm bringing up my bugs on your post, but what the hey
     
  6. John DiMartino

    John DiMartino PlowSite.com Veteran
    Messages: 2,154

    If it was a fuel problem,usually it is worse under a load,when using a lot of gas.How is it wide open?Its no worse,stop looking there.I think you have an ignition coil going out or a bad module.Do you have a tachometer?If so,does it die and bounce around when the engine cuts out?You can replace the fuel filter cheap,so see what it looks like.
     
  7. Spence

    Spence Junior Member
    Messages: 13

    I just had a new carb. installed, so it has a new fuel filter. The reason the carb. was replaced is that the choke was shot, the whole carb. was worn out. It has done been rebuilt a couple of times. It does seem to be worse under a load, or when you hit the accelerator a little harder. I did a tune-up today; new plugs, wires, dist. cap, and rotor. Didn't fix it, still does the same thing. I was told that a way to check for a vacuum leak around the intake was to spray starting fluid around the intake. If there was a leak, the engine would rev up. I did that today too. I sprayed around the intake, fittings on the intake, and the carb. The engine never reved up. I sprayed eveywhere the best I could, although I may have missed a couple of spots. Now I'm back where I started, maybe it is the fuel pump. Don't know, need some help.
     
  8. mike reeh

    mike reeh Senior Member
    Messages: 114

    Its the fuel pump..

    Even if its not, its still good measure to change it because when they go out, they tend to just go out without warning, at the worst possible time, in the worst possible place.

    I insist on Delco brand, most cheap parts stores carry them for 15-25 dollars.. its not hard to change, make sure you have a flare nut wrench, so you dont round off the flare tubing fittings.. that is the WORST. good luck

    mike reeh
     
  9. Power mad

    Power mad Member
    from Oregon
    Messages: 75

    I don't want to start a dispute, but throwing parts at a problem to see if it fixes the bug is not only costly, but can be a frustrating waste of time. I also was an auto tech for a while, and that was how the owner of one shop I worked at fixed things. Very unprofessional, I watched other mechs throw parts at a bug and after hundreds of dollars in unnessesary parts they eventualy fixed the problem, to me that is embarrassing and unethical. I had no diagnostic equipment to work with other than Fluke V/O meter. I had a diagnostic manual and could find the values for different sensors and would spend hours finding the problem. But I never replaced anything unless I knew for a fact that it was faulty. And as I was working flat rate it hurt me , But my reputation as good mechanic was worth it. I finaly quit in disgust over the whole thing, I am a deisel mech after all and was only doing this to get by until I was back in my normal feild. But it was a learning experience that I am gratefull to have had, I am always eager to learn new things . You never know when they will come in handy.
    All done with the sermon
    Ron
     
  10. Larrytow

    Larrytow Junior Member
    Messages: 28

    I would say to check out the two wires that go to the ign module from the pick up coil. More than likely they are cracked and ready to break off right where they go into the pick up.If one or both break off the motor will stop running. This is a very common prob on this motor due to the advance mechinism pulling on the wires when the timing advance kicks in.

    Regards, Larry
     
  11. John DiMartino

    John DiMartino PlowSite.com Veteran
    Messages: 2,154

    Larry,maybe im wrong,but i thought the 83;s had electronic adveance thru the ECM,i never asked if it had a feedback carb,depending on if its 1/2,3/4,or 1 ton.If it has a vacuum advance then it is a common problem,you can just unplug the vacuum advance and plug it,then go for a drive,if its better you found the problem.I have seen thsi a lot too,just though this one was a feedback carb model CCC.
     
  12. Larrytow

    Larrytow Junior Member
    Messages: 28

    John D., you might very well be right about it having electronic advance. I did not look up what system 83s had before I posted.It's hard to remember what sys is in what year. Especialy when you try to diagnose over the net. If it does have vac advance, you told him exactly how to diagnose it. Thats what I would have recomended also.

    Regards, Larry
     
  13. Spence

    Spence Junior Member
    Messages: 13

    It does have a vacuum advance. So what I should do then is unplug it from the carb., plug the line, and drive it. If it drives better, or without cutting out, then the vacuum advance needs to be replaced. If it's not any better, or still cuts out, then that ain't the problem. Right?
     
  14. Larrytow

    Larrytow Junior Member
    Messages: 28

    Spence, You got it kinda confused. If you pull the vac advance hose off the dist and then drive it, if it does not cut out ,then the pick up coil in the dist is NG. If it does not make any diff , then you have some other prob. John DiMartino told you this also. If the pick up coil is bad ( as I figgured) then you need to pull the dist out of the motor to fix it. Because you need to remove the shaft of the dist to replace the pick up. If that is the case and you dont know how to proceed, post your questions here an we will try to advise you. PLEASE NOTE: if you take the cap off and even touch those wires, they may be so far gone that they may break with the slightest pull on them. Like I said; VERY COMMON prob. Let us know what you determine about this; It's always good to know if we are helpfull or not.

    Regards, Larry
     
  15. Larrytow

    Larrytow Junior Member
    Messages: 28

    Spence, I'm not sure I made it clear. THe vac advance has nothing to do with your prob. It is only the thing that makes the pick up coil act up . The pick up is the prob; not the vac advance.

    Regards, Larry
     
  16. 4x4k20

    4x4k20 Member
    Messages: 72

    change your fuel pump.
     
  17. Spence

    Spence Junior Member
    Messages: 13

    Larry, I did the test you talked about tonight. Still did it when I unplugged the vacuum line. Its going to the shop tomorrow morning . Maybe they can figure out something. I still wonder if it is the fuel pump, just don't know. I'm going to get them to check the timing, test the fuel pump, check and see if they can find a leak in the intake, and any thing else they feel is necessary. I can't find a leak in the intake, but I don't know what all to look for. I just want my truck fixed.
     
  18. mike reeh

    mike reeh Senior Member
    Messages: 114

    round of beers, on spence, if its the fuel pump :)
    round of beers, on me, if its not (no cheating!)

    mike reeh
     
  19. Larrytow

    Larrytow Junior Member
    Messages: 28

    OK, its not the pick up then. If its a fuel supply prob, it might not be te pump tho_On older trks I have seen rusted out fuel lines that did not leak but still allowed air to be sucked in. Something to check anyhow.

    Regards, Larry
     
  20. 3/4tonTodd

    3/4tonTodd Member
    Messages: 63

    My 76 started cutting out last fall after I replaced my carb with a reman Quadrajet (Holley rebuilds them). Turned out to be the oddest thing I've ever seen. What I thought was a fuel filter on the main fuel line to the engine turned out to be a check valve installed backwards. I replaced it with a see through Wix inline filter and the problem is gone. Makes me wonder what else the previous owner did to this truck!

    Have you had the ignition module checked? Some auto parts stores have a tester in the store and will check them for free. Just take it out of the truck and take it into them (if you have one of those stores in your area!)

    Anyway, good luck with it.

    Todd