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Noob with engine issues

Discussion in '1973-1991 K5 Blazer | Truck | Suburban' started by Element, Mar 23, 2007.

  1. Element

    Element 1/2 ton status

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    Hey guys, bit of a noob to full-size 4x4s here, although I've had an S-10 ZR2 previous to the K5.

    Anyway, directly to the topic. Earlier this week, I bought a 1987 K5, something like 8" of suspension lift, TH350 conversion, with a bone-stock 350 with 87k on the clock under the hood. First few days of driving were fine, engine was a bit rough but I figured that was simply from working the kinks out - it hadn't been driven more than 5 times over the past year. However, yesterday and today, the engine's gotten very tempermental. It idles horribly when cold, where the rpms drop so low as to almost stall the truck out. When I come to a stop, the engine either typically nearly stalls, or cuts out completely. It also does this about 50% of the time when I put it in reverse. Four times now, the engine has cut out and won't restart (or stay running when I restart it) unless I pump the pedal when the engine is cranking, then stomp the gas as soon as it fires up.

    Another known issue is a dead fuel sending unit, which isn't a big deal, as I was planning on replacing that along with the fuel pump in a few weeks. Since I don't know what kind of maintenance has been performed before I bought it, I'd prefer to take a proactive stance on fixing things, so I don't get stuck on the side of the road.

    The biggest issue that's a concern to me is the oil pressure. It's fine when cold, and goes from 30-40psi when I'm driving (according to the LED gauge that's wired up, as the stock one in the dash is stuck and needs fixed). However, at low rpm, such as driving through town, or when sitting still, it occasionally dips as low as 8psi. I expect the pressure to be a bit low, since it is an older engine, but my Trans Am typically sits right at 40psi when idling. I know, different engine and all, but 8psi seems dangerously low to me. I know the gauge could be showing a faulty pressure, but it still worries me. I plan on having the engine rebuilt to make a bit more power in the future, but I don't want to have to do it before I want to, due to a spun bearing or anything.

    I know I have an issue with the transfer case - the rear seal where the output shaft comes out is leaking and needs replaced, and the fluid coming out resembles gravy...I figure since it sat so long, some water condensed in the case and glopped the fluid up. It's going in the shop next week for ball joints, an alignment, and an inspection, and I'm going to have the case flushed, refilled, and the seal replaced then. I don't think this could be causing any problems with the engine, other than occasionally the truck will buck forward while stopped, but I've been attributing the engine nearly stalling out, then kicking back in while the truck is in drive.

    I've got new plugs, wires, a cap, and rotor ready to go in this weekend, and I'll be getting a new alternator and battery shortly, just as preventative maintenance. My two biggest questions are this - what are some of the most likely culprits for the engine problems? I'm going to be cynical and not expect the parts I bought to fix anything, so I want to know what the best route to go with this would be. Fuel pump? Doesn't seem likely, since the truck idles fine 50% of the time, and is fine when driving - no bucking or anything like that. Sensors? I'm used to LSx engines, so I'm not sure what sort of sensor suite the TBI has on it, nor which one could cause issues like this. TPS? Other question is, how hard is it to install a new oil pump? That's definitely a high-priority for me, as I don't really like my engines to run with less than 25psi, minimum, at idle. I've got a garage full of tools, and have plenty of experience wrenching on my T/A, but i don't know how much of that will translate over to an SBC K5.

    Sorry for the long post, just figured it'd be better to explain the entire situation in one post, instead of answering questions in a page of posts.
     
  2. ryoken

    ryoken Puppy Fabricator Premium Member GMOTM Winner

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    first thing you should be doing is an oil change...

    second is see if it's throwing any codes... using the ole paper clip... learn here...

    http://www.cfm-tech.com/gm_tbi_trouble_codes.htm

    third, before I'd worry about the pump, definitely throw a filter in it... I'd also give it a Seafoam treatment, couple cans right in the tank...

    If it's not throwing any codes, we can go from there... plugs, cap and rotor can do wonders sometimes...
     
  3. Element

    Element 1/2 ton status

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    Yeah, I have oil and a filter, as well as a fuel filter, going in on Sunday also.

    I'll try pulling the codes and see if that nets anything, too.
     
  4. 4X4HIGH

    4X4HIGH 1 ton status Premium Member GMOTM Winner

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    Let me first start by saying that if the gas that's in it is a year old you need to drain it completely. Bad gas can do the exact things you're described.

    Next thing is your tranny. If it had a 700R4 in it prior to someone installing a TH350 then the ECM is going to pull a code for no TCC. You should have an SES light that comes on and a code to go along with it. You need to have a chip burnt to get rid of the TCC issue.

    Third, i would not rule out a bad fuel pump. I had one go bad once and it would drive normal around town and sometimes normal at highway speeds but sometimes it would buck on me.
     
  5. sweetk30

    sweetk30 professional hooker Premium Member

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    to save you some time possibly. what kind of plugs were you going to install? thay best be ac delco for the tbi motor i hope. and what ever you do dont use bosch platnium trash plugs in a american motor. i know those parts guys love to push them on sales.

    i would start off on the full tune up/ oil change / fuel filter and the other little goodys you have so far. then get a bottle of injector cleaner or some thing along those lines and a tank of prem fuel to run the junk out if you can get most of the old out first then please do so.
     
  6. Element

    Element 1/2 ton status

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    NGK plugs going in - I don't waste money on Bosch anything, especially after seeing what some of the "magical" +4 plugs have done to engines. I've had really good results with the NGKs in my LS1, so I figured I'd just stick with them.

    The gas in the tank is fresh, as it was nearly empty when I picked it up and put nearly 20 gallons in it when I stopped by a gas station.

    I've got a can of Seafoam in the gas tank, and I'm going to run some through the brake booster line tomorrow and see how it cleans the top end up, plus doing the other maintenance stuff, and I'll see where that gets me. I'll also try pulling the codes to see if anything comes up...I couldn't get any info on the guy who did the TH350 swap (although I still don't understand why he did it) to see if he had the chip issue dealt with or not, but I'll find out tomorrow.
     
  7. sweetk30

    sweetk30 professional hooker Premium Member

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    just my opinion as a mechanic but those ngk plugs work good in jap stuff great and possibly newer stuff. but our old trucks just seem to like the good old acdelco stuff. but give it a try and let us know how it goes.
     
  8. ryoken

    ryoken Puppy Fabricator Premium Member GMOTM Winner

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    NGK's are the closest plug to an AC imo from what I've seen.. Construction/style looks almost indentical... How they run, debatable I guess..

    Look nothing like a Bosch, Champion, etc...

    I hate Boschs in american motors.. and well, hate Champions all the time! :haha:
     
  9. duallyjams

    duallyjams 1/2 ton status

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    My 87 tbi did exactly the same thing you described.The fuel pump is susposed to 14 psi it was 5 psi changed fuel pump and filter 3 months ago no more problems. :D
     
  10. Element

    Element 1/2 ton status

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    Well, got everything put on, and now the thing cranks but won't fire :o

    Think I might have messed the wires on the distributor up (don't think so, but who knows) so I'm looking for a wiring diagram of the plug wire sequence on the distributor.

    Fixed the wire sequence...it was all screwed up. Idles better, just have to wait until tomorrow to see how it does as far as dying.
     
    Last edited: Mar 25, 2007
  11. kirkallen143

    kirkallen143 Registered Member

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    18436572 firing order.
    make sure bat. terminal is plugged into the dist cap.

    Kirk
     
  12. Element

    Element 1/2 ton status

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    Got the firing order thing taken care of, and now the engine hasn't shut off at a stop - yet. Tried to pull the codes by using the jumper pin method, but there wasn't an SES light anywhere on the dash. Doesn't light up when the key is set at Run, either.
     
  13. SkysTheLimit

    SkysTheLimit 1/2 ton status

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    SES bulb is probably out then if it doesn't flash when you cycle through the ignition.

    It's not too bad to remove the guage cluster, just be careful with the printed circuit on the back of the cluster. Actually kind of a cool setup. While you got it out, might as well check all the other bulbs and do the mod where you paint the rear of the bezel with chrome/silver paint to brighten it up.
     
  14. sweetk30

    sweetk30 professional hooker Premium Member

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  15. Element

    Element 1/2 ton status

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    Interesting...might do that this weekend. Assuming I can fix the damned broken fuel line. If it's not one thing, it's another...
     
  16. BulldogK5

    BulldogK5 1/2 ton status GMOTM Winner

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    Is everything still good. I am curious about the plugs and other parts that you did use. I am gathering parts for a major tune-up and trying to see what is working best. Mine is a '91 350.
     
  17. Element

    Element 1/2 ton status

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    Well, it runs better, but the engine still cuts out occasionally. I think the alternator might be going out, since it only happens when I come to a stop, and normally runs fine otherwise. Probably just going to have the engine rebuilt, as the oil pressure is still only around 5-6psi at hot idle, and it's making a strange rattling/clicking noise on acceleration.
     

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