Welcome to Club Hot Rod!  The premier site for everything to do with Hot Rod, Customs, Low Riders, Rat Rods, and more. 

  •  » Members from all over the US and the world!
  •  » Help from all over the world for your questions
  •  » Build logs for you and all members
  •  » Blogs
  •  » Image Gallery
  •  » Many thousands of members and hundreds of thousands of posts! 

YES! I want to register an account for free right now!  p.s.: For registered members this ad will NOT show

 
Like Tree26Likes

Thread: Sick L98
          
   
   

Reply To Thread
Page 1 of 2 1 2 LastLast
Results 1 to 15 of 19
  1. #1
    mr-natural is offline CHR Member Visit my Photo Gallery
    Join Date
    Jan 2018
    Location
    SCOTTSDALE
    Posts
    34

    Sick L98

     



    58 Corvette with 1987 L98 engine, stock ECM, external Walbro fuel pump: Running great for months, then died one time 5 miles from home a while back, and immediately restarted - drove home with no problem. Then later, about 5 miles from home started coughing through the intake and sputtering (just like earlier) - eventually died after turning around to head back home. Waited 40 minutes restarted but hardly ran - called tow truck - embarrassing. Once home the car restarted - barely running but noted small amount of white smoke from left exhaust. Never any codes were thrown. Reset lifters from one turn past zero to 3/4 turn. Vacuum is good at 15 - 17". Checked compression and it was all around 120-130 PSI. #5 & 7 spark plugs are just a bit darker than all the others. Did coolant pressure check and it was good. Started and it was smooth and solid - went for test ride and performed well. Stopped at a neighbors about 300 yards from home - spent maybe 3 hours - went to drive back home and barely made it back. Engine would either run good for a short while or start sputtering and backfiring. Thankfully it ran strong for a few seconds to get me up my driveway and into the garage. Recently replaced everything in the distributor – no change. Runs terrible with the TPS connected or disconnected. I believe my grounds are good but I could be missing something there. Fuel pressure comes up to 45 PSI but will bleed down to 5 PSI within a few minutes. I then had someone turn on ignition in order to bring pressure up and I immediately shut the valve between the fuel tank and the pump. Same thing – pressure bled off in about 3 minutes to about 5 PSI then it takes a long time to go to zero. Any suggestions?

  2. #2
    NTFDAY's Avatar
    NTFDAY is online now CHR Member Visit my Photo Gallery
    Join Date
    Aug 2003
    Location
    Springfield
    Car Year, Make, Model: '66 Mustang, 76 Corvette
    Posts
    4,941

    IMHO your problem is in the tank, either electrical or half plugged with gunk. If the tank is stock I would bet the outlet is partially plugged. I had a problem similar to what you are describing many years ago with a 57 Bel-Air 2dr hardtop and a contaminated tank was the problem.
    Ken Thomas
    NoT FaDe AwaY and the music didn't die
    The simplest road is usually the last one sought
    Wild Willie & AA/FA's The greatest show in drag racing

  3. #3
    rspears's Avatar
    rspears is offline CHR Member/Contributor Visit my Photo Gallery
    Join Date
    Sep 2007
    Location
    Gardner, KS
    Car Year, Make, Model: '33 HiBoy Coupe
    Posts
    10,028

    I'd say Ken could well be right. Have you checked/changed your fuel filter? I remember my '71 Charger and a questionable Houston neighborhood one afternoon.......
    NTFDAY and 36 sedan like this.
    Roger
    Enjoy the little things in life, and you may look back one day and realize that they were really the BIG things.

  4. #4
    mr-natural is offline CHR Member Visit my Photo Gallery
    Join Date
    Jan 2018
    Location
    SCOTTSDALE
    Posts
    34

    Quote Originally Posted by NTFDAY View Post
    IMHO your problem is in the tank, either electrical or half plugged with gunk. If the tank is stock I would bet the outlet is partially plugged. I had a problem similar to what you are describing many years ago with a 57 Bel-Air 2dr hardtop and a contaminated tank was the problem.
    NTFDAY & RSPEARS I don't think that's the problem for the following reasons: Runs great every so often. I coated the interior of the tank a few years back and recently opened up the top and it looks clean inside. The filter between the tank and the fuel pump remains clean. I used to have a submersible pump and modified the top of my tank to accommodate the pump and fuel level sending unit so I have great visibility into the tank. Another fellow recommended I change out the CTS and I'm going to try that - right before I pull my hair out.

  5. #5
    rspears's Avatar
    rspears is offline CHR Member/Contributor Visit my Photo Gallery
    Join Date
    Sep 2007
    Location
    Gardner, KS
    Car Year, Make, Model: '33 HiBoy Coupe
    Posts
    10,028

    First I don't know what the "CTS" is, but because of your statement about the fuel pressure leakdown I'll toss out another thought. I was having intermittent starting issues with my '05 Jeep, and I changed just about every sensor it had - Crank Position, Cam Position, Throttle Position and finally took it to a buddy of mine who had a repair shop. After chasing things for most of a day he found that three of the six injectors were leaking down, bleeding off pressure and wouldn't hold against the pump head. I told him to change them all, and it was like a different engine. Wondering if perhaps you've got some bad injectors?
    Roger
    Enjoy the little things in life, and you may look back one day and realize that they were really the BIG things.

  6. #6
    johnboy is offline CHR Member Visit my Photo Gallery
    Join Date
    May 2005
    Location
    Tataraimaka NZ
    Car Year, Make, Model: `47 Ford sedan, A.C.Cobra replica.
    Posts
    2,218

    I had a similar problem with the Cobra some years ago. We too tried everything we could think of but to no avail.
    It would run sweet as a nut for hundreds of miles, never missing a beat, then suddenly it would go ape.
    In the finish, after twelve months or more of this, I pulled the fuel tank out and cleaned it thoroughly...and out came a waxed candy wrap paper that some little a$$wipe had dropped in.
    No more problem after that.
    We surmised it had blocked the outlet, when the motor stopped, so did the suction, and it drifted away.
    Only to return at a later time/date.

    So I feel for your frustration.
    And the fuel tank could be a good place to look.

    (And I put a filter on the filler-pipe to the tank.)
    Last edited by johnboy; 12-23-2020 at 07:31 PM.
    NTFDAY, 40FordDeluxe and 36 sedan like this.
    johnboy
    Mountain man. (Retired.)
    Some mistakes are too much fun to be made only once.
    I don't know everything about anything, and I don't know anything about lots of things.

    '47 Ford sedan. 350 -- 350, Jaguar irs + ifs.
    '49 Morris Minor. Datsun 1500cc, 5sp manual, Marina front axle, Nissan rear axle.
    '51 Ford school bus. Chev 400 ci Vortec 5 sp manual + Gearvendors 2sp, 2000 Chev lwb dually chassis and axles.
    '64 A.C. Cobra replica. Ford 429, C6 auto, Torana ifs, Jaguar irs.

  7. #7
    40FordDeluxe's Avatar
    40FordDeluxe is offline CHR Member Visit my Photo Gallery
    Join Date
    Apr 2011
    Location
    Prairie City
    Car Year, Make, Model: 40 Ford Deluxe, 68 Corvette, 72&76 K30
    Posts
    6,864
    Blog Entries
    1

    Have you checked the fuel pressure when it is running like garbage? That would help with diagnosing the issue. External pumps are prone to failure due to heat and lack of cooling. How far from the tank is your pump? Leaking/sticking/gummed up injectors could be it too. We had a 91 TPI Vette years ago that was running similar and we found after many hours working on it that the coolant temp sensor was shorted telling the computer the engine was over heating but the gauge showed normal. It ran all sorts of goofy. That car was probably the most finicky TPI car I was ever around.
    Dave Severson, NTFDAY and rspears like this.
    Ryan
    1940 Ford Deluxe Tudor 354 Hemi 46RH Electric Blue w/multi-color flames, Ford 9" Residing in multiple pieces
    1968 Corvette Coupe 5.9 Cummins Drag Car 11.43@130mph No stall leaving the line with 1250 rpm's and poor 2.2 60'
    1972 Chevy K30 Longhorn P-pumped 24v Compound Turbos 47RH Just another money pit
    1971 Camaro RS 5.3 BTR Stage 3 cam, SuperT10
    Tire Sizes

  8. #8
    mr-natural is offline CHR Member Visit my Photo Gallery
    Join Date
    Jan 2018
    Location
    SCOTTSDALE
    Posts
    34

    Quote Originally Posted by rspears View Post
    First I don't know what the "CTS" is, but because of your statement about the fuel pressure leakdown I'll toss out another thought. I was having intermittent starting issues with my '05 Jeep, and I changed just about every sensor it had - Crank Position, Cam Position, Throttle Position and finally took it to a buddy of mine who had a repair shop. After chasing things for most of a day he found that three of the six injectors were leaking down, bleeding off pressure and wouldn't hold against the pump head. I told him to change them all, and it was like a different engine. Wondering if perhaps you've got some bad injectors?
    RSPEARS, CTS stands for Coolant Temperature Sensor, which I just finished installing and wouldn't you know I've got the same problem. Dog turd!!! I've got a new fuel filter which I'll stick in but I'd be real surprised if that was the cure. I guess my next question is: Since I obviously have fuel leaking somewhere it MUST be through one or more of the Bosch injectors - which aren't all that old. I have not found out how to troubleshoot which injector is leaking. Do you have any reference to how to trouble shoot that issue?

  9. #9
    mr-natural is offline CHR Member Visit my Photo Gallery
    Join Date
    Jan 2018
    Location
    SCOTTSDALE
    Posts
    34

    Quote Originally Posted by 40FordDeluxe View Post
    Have you checked the fuel pressure when it is running like garbage? That would help with diagnosing the issue. External pumps are prone to failure due to heat and lack of cooling. How far from the tank is your pump? Leaking/sticking/gummed up injectors could be it too. We had a 91 TPI Vette years ago that was running similar and we found after many hours working on it that the coolant temp sensor was shorted telling the computer the engine was over heating but the gauge showed normal. It ran all sorts of goofy. That car was probably the most finicky TPI car I was ever around.
    40Ford you sure have an interesting selection of cars, one for any occasion - sounds like the way to go. I'll take your suggestion and get my wife out here to check fuel pressure when I'm trying to get it to run. It hasn't run good for a few days now - just coughing & sputtering & backfiring and never taking any throttle.
    40FordDeluxe likes this.

  10. #10
    firebird77clone's Avatar
    firebird77clone is offline CHR Member Visit my Photo Gallery
    Join Date
    Sep 2005
    Location
    Hamilton
    Car Year, Make, Model: 69 nomad, 73 charger, 74 vega
    Posts
    3,668

    Mr Natural

    I am just thinking out loud, never having trouble-shooted that particular issue: maybe pull the plugs, and swab the cylinders. Wet swab = leaky injector.
    .
    Education is expensive. Keep that in mind, and you'll never be terribly upset when a project goes awry.
    EG

  11. #11
    rspears's Avatar
    rspears is offline CHR Member/Contributor Visit my Photo Gallery
    Join Date
    Sep 2007
    Location
    Gardner, KS
    Car Year, Make, Model: '33 HiBoy Coupe
    Posts
    10,028

    Quote Originally Posted by mr-natural View Post
    I have not found out how to troubleshoot which injector is leaking. Do you have any reference to how to trouble shoot that issue?
    My mechanic friend lifted the fuel rail & injectors clear of the intake leaving the injector electrical clips in place, blocked it up so he could see the injector tips and energized the system which puts pump pressure on the rail with the engine off. I think he said that two or three of six were dripping, not at the same rate so I had him replace all six.

    Another thought - on my '33 with Edelbrock injection, my Fuel Pressure Regulator failed and was sucking raw fuel through the diaphragm. I called Edelbrock and the Tech knew immediately that my FPR was leaking and sent me a new one. For troubleshooting, I copied this from an OEM forum -
    "Did you check the FPR by pulling the vacuum line off while the engine is idling?? Just pulling the vacuum line off may not show if there is leakage past the diaphragm as the fuel will get sucked away by the vacuum and thru the vac line and into the intake. Pull the vac line off while the engine is idling and plug it(the vac hose, not the nipple on the FPR). Let it idle for several minutes and watch the vac nipple on the FPR for any signs of fuel leakage."
    Roger
    Enjoy the little things in life, and you may look back one day and realize that they were really the BIG things.

  12. #12
    jerry clayton's Avatar
    jerry clayton is offline CHR Member Visit my Photo Gallery
    Join Date
    Feb 2006
    Location
    Bartlett
    Posts
    6,823

    Whenever you are checking fuel system problems----------know where a workable fire extingser is nearby--------don't have any vehicle sitting just outside the garage door------------don't have anything between the car your working on and the door-----------just so you can do something if it catches on fire------

    we went to help a customer with his first time fire up of a hemi we built----the drive way was blocked outside the door-why not-hemi car had not moved for months------wellllllllllllllllll
    By popular opinions-just a grumpy old man key board bully--But really, if you are going to ask for help on an internet site, at least answer questions about what you are asking about-----

  13. #13
    36 sedan's Avatar
    36 sedan is offline CHR Member Visit my Photo Gallery
    Join Date
    Apr 2012
    Location
    american canyon
    Car Year, Make, Model: 36 Ford Sedan, 23 T Bucket
    Posts
    1,821

    ^^^^ SAGE advice!!

  14. #14
    mr-natural is offline CHR Member Visit my Photo Gallery
    Join Date
    Jan 2018
    Location
    SCOTTSDALE
    Posts
    34

    Well, I've been letting my lumbar fuse for the past two months so now I'm back into it. After lots more farting around I came up with, using the wise advice of a good friend, a distributor problem. A new drive gear and proper shimming to .013" end play I now have and engine that starts and sounds good - for 5 to 10 seconds then it dies. That is with the timing lead disconnected that goes to the ECM. When that lead is reconnected the engine will run longer but still dies after a few minutes. Watching the timing light reveals that the ignition is shutting down to cause the death. I monitored the battery voltage at the distributor and it stays hot during the death. All components in the distributor are new including cap. Fuel pressure holds fine during those few seconds when all is well. Any ideas are welcome. ECM?

  15. #15
    rspears's Avatar
    rspears is offline CHR Member/Contributor Visit my Photo Gallery
    Join Date
    Sep 2007
    Location
    Gardner, KS
    Car Year, Make, Model: '33 HiBoy Coupe
    Posts
    10,028

    Take good care of that back!

    Looking back through your first post you said,
    Quote Originally Posted by mr-natural
    I believe my grounds are good but I could be missing something there.
    It doesn't cost much to ensure that your grounds are good, and good grounds are critical. I'd say verify your battery to chassis ground, your engine block to chassis ground and your alternator case ground. Star washers are your friend, especially on painted surfaces.
    Once your grounds are confirmed if you still have the problem I'm thinking your idea of the ECM being bad may be the culprit.
    glennsexton likes this.
    Roger
    Enjoy the little things in life, and you may look back one day and realize that they were really the BIG things.

Reply To Thread
Page 1 of 2 1 2 LastLast

Tags for this Thread

Posting Permissions

  • You may not post new threads
  • You may not post replies
  • You may not post attachments
  • You may not edit your posts
Links monetized by VigLink