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Thread: Back four cylinders cold.

  1. #1

    Default Back four cylinders cold.

    Hi all. My system is a Stealth Ram on a 350 SBC, Holley Avenger MPFI, and Holley small cap distributor. Ran good the first 100-200 miles and yesterday died coasting down a gravel road, it started up and made it home running terrible. So far I've spoke with Holley tech and I checked fire on plugs on dead cylinders and was blue. I ran through settings on my handheld which is all I have and it all looks correct by what Holley says. I also switched front injector wires to rear and vice versa, still cold headers in the rear. A cheap rental fuel pressure gauge shows 38 psi is this enough? Be gentle on me I'm new to the world of fuel injection. Also last week, I did have my modulator valve go bad and it was teed into my MAP sensor vacuum line, and some transmission fluid did get in the MAP sensor. Holley tech said this wouldn't cause the back four to be cold?

  2. #2
    Join Date
    Dec 2009
    Location
    Connecticut
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    Fuel pressure is supposed to be 43 psi. Replace the MAP sensor.
    May God's grace bless you in the Lord Jesus Christ.
    '92 Ford Mustang GT: 385" SBF, Dart SHP 8.2 block, TFS TW 11R 205 heads, 232°-244° duration/.623" lift/114° LSA camshaft, 11.8:1 comp, TFS R-Series FTI ported intake, Dominator MPFI & DIS, 36-1 crank trigger/1x cam sync, 200A 3G alternator, Optima Red battery, A/C, 100HP progressive dry direct-port NOS, Spal dual 12" fans/3-core Frostbite aluminum radiator, Pypes dual 2.5" exhaust/off-road X-pipe/shorty headers, S&W subframe connectors, LenTech Strip Terminator wide-ratio AOD/3000 RPM converter, FPP aluminum driveshaft, FPP 3.31 gears, Cobra Trac-Lok differential, Moser 31 spline axles, '04 Cobra 4-disc brakes, '93 Cobra booster & M/C, 5-lug Bullitt wheels & 245/45R17 MT tires.

  3. #3

    Default

    OK, thank you Danny. I'll order a MAP sensor and fuel pump today. Is Holley the best way to go on the new pump?

  4. #4
    Join Date
    Dec 2009
    Location
    Connecticut
    Posts
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    A Holley/Walbro 255 LPH fuel pump (LINK) will suit you just fine. Or contact Chris Myer at EFISystemPro.com or Fuel-Pumps.net. He's a Holley EFI parts professional/fuel pump specialist.

    https://forums.holley.com/showthread...220#post226220 (Additional Information/Related Forum Post)
    May God's grace bless you in the Lord Jesus Christ.
    '92 Ford Mustang GT: 385" SBF, Dart SHP 8.2 block, TFS TW 11R 205 heads, 232°-244° duration/.623" lift/114° LSA camshaft, 11.8:1 comp, TFS R-Series FTI ported intake, Dominator MPFI & DIS, 36-1 crank trigger/1x cam sync, 200A 3G alternator, Optima Red battery, A/C, 100HP progressive dry direct-port NOS, Spal dual 12" fans/3-core Frostbite aluminum radiator, Pypes dual 2.5" exhaust/off-road X-pipe/shorty headers, S&W subframe connectors, LenTech Strip Terminator wide-ratio AOD/3000 RPM converter, FPP aluminum driveshaft, FPP 3.31 gears, Cobra Trac-Lok differential, Moser 31 spline axles, '04 Cobra 4-disc brakes, '93 Cobra booster & M/C, 5-lug Bullitt wheels & 245/45R17 MT tires.

  5. #5
    Join Date
    Jan 2010
    Location
    Brisbane, Australia
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    Let's see, you have injector pulse and spark, and the engine runs on the front four cylinders?
    Can you remove all eight spark plugs and conduct a compression test please?
    I've seen a broken camshaft behind the center bearing cause this issue. Gary
    Regards, Gary

  6. #6

    Default

    Gaz64, I will check compression tomorrow, I had a thought of this today. Also, I spoke with Holley earlier and they said to run my vacuum line to the ECU vacuum port and change setting in handheld to internal 1 bar. So I did and same so far. I'll check compression and report back.

    OK, so I figured something out today. I had a bent pushrod on #8 cylinder and the rocker arm was turned off to the side, but what confused me was the intake valve was stuck open, so zero compression. I stuck a scope in the spark plug hole and inspected the best I could, tapped on the top of the valve stem and it came back up. I put a new push rod in and bumped it over several times while watching it work up and down, 180 psi on compression, started and runs good again. What happened? I think I'll replace the lifters since I didn't in my rebuild and I know that wasn't smart. Watching the valve while bumping it over, it didn't stay opened like the lifter is bleeding off, but I'm not sure how long a hydraulic lifter will hold a valve open?

  7. #7
    Join Date
    Jan 2010
    Location
    Brisbane, Australia
    Posts
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    Didn't replace the lifters? The ONLY reason you ever do this, is if the same camshaft went back in AND the lifters went back in the order they came from. If the lifters got mixed up at all, instantly in the trash they go. Now your engine should've only been misfiring on cylinder #8, so how are the other three now OK? I'd be checking your lifter preload. Gary
    Regards, Gary

  8. #8

    Default

    AEM 50-1000 is a great in-tank pump and I personally know of two guys running this pump with supercharged small blocks that are in excess of 550 flywheel HP, and have had trouble free operation for over 20K miles. Jegs currently has it for sale for $91. It's a well built piece. I only mention this because when I looked for the Walbro in-tank it was:
    1) Almost twice the price.
    2) Was a substantial lead time.
    3) And there have been a lot of counterfeit Walbro pumps flooding the market.

  9. #9
    Join Date
    Dec 2009
    Location
    Connecticut
    Posts
    24,126

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    Quote Originally Posted by Bill C View Post
    I only mention this because when I looked for the Walbro in-tank it was:
    1) Almost twice the price.
    2) Was a substantial lead time.
    3) And there have been a lot of counterfeit Walbro pumps flooding the market.
    http://www.fuel-pumps.net/walbro-forgeries.html (Buy Holley or other legitimate source.)
    May God's grace bless you in the Lord Jesus Christ.
    '92 Ford Mustang GT: 385" SBF, Dart SHP 8.2 block, TFS TW 11R 205 heads, 232°-244° duration/.623" lift/114° LSA camshaft, 11.8:1 comp, TFS R-Series FTI ported intake, Dominator MPFI & DIS, 36-1 crank trigger/1x cam sync, 200A 3G alternator, Optima Red battery, A/C, 100HP progressive dry direct-port NOS, Spal dual 12" fans/3-core Frostbite aluminum radiator, Pypes dual 2.5" exhaust/off-road X-pipe/shorty headers, S&W subframe connectors, LenTech Strip Terminator wide-ratio AOD/3000 RPM converter, FPP aluminum driveshaft, FPP 3.31 gears, Cobra Trac-Lok differential, Moser 31 spline axles, '04 Cobra 4-disc brakes, '93 Cobra booster & M/C, 5-lug Bullitt wheels & 245/45R17 MT tires.

  10. #10

    Default

    Still, the 340 LPH arm pump is 91 bucks, readily available. And a proven performer from mild street stuff to wild boosted higher RPM setups. It's just commonly used in import circles. However it's of excellent quality. Try one!

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