No Power, pops out back, runs hot, and Pi$$ me off

Discussion in 'Classic Mustang Specific Tech' started by mustangman1974, Jul 26, 2008.


  1. mustangman1974

    mustangman1974 Member

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    Ok I have been dealing with a problem that, because of the warm days has gotten worse, or more likely I am now driving it when its hot.

    The car starts runs fine until the temp gets to 200 then I start getting some misses on occassion. At about 210-220 it like its hitting a rev limiter and poofs out the back. Its not a back fire because it sure ain;t loud. If I turn the heater on and cool the car down below 200 the problem disappears. Happens at any speed. IF I am on the freeway and it starts I can get at current throttle and its fine, but If I go up hill or give it gas it acts like it has noting to give, and stumbles.

    Heres what I currently got:

    5.0 - 34k miles on rebuild motor.
    unfortunately the cobra cam was replaced with the explorer cam by Ford.
    comp 900 distributer MBI
    Promaster coil
    9mm wires
    edlerbock rpm manifold
    edlebrock 1405 carb
    edlebrock victjr fuel pump (first changed from standard edlebrock pump I though it was vapor locking)
    Holley regulator
    A/C

    Timing 10 degrees at 800 rpm 34 at 3,500
    vacuum bounces between 16.5-17.5 at 800 rpm
    increases to almost 2 in. when in drive between 14-16.
    idle in gear 660-690.

    What they heck can I check?:shrug:
  2. STSFCTN67

    STSFCTN67 New Member

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    I still have a similar issue going on with mine, I am checking the fuel lines to make sure they are not near the headers. I am checking for vapor lock, I am checking the sending unit. I have already adjusted the floats in the carb, made sure my gas cap was vented and checked the electrical. It sounds like vapor lock for you at the carb?? I cant go uphill at all it just dies?
  3. TOM B

    TOM B New Member

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    First thing is its getting to hot and starts to stumble, is the water pump and radiator the correct size, is the water pump running in the correct direction, did someone change the water pump, is it a reverse rotation pump?
    If all the common things are good then I would check the cam timing, someone my have tried to advance or retard the cam and did it wrong or took it to far. this will cause the engine to over heat also as the valves could glow red and loose there sealing property.
    Is the cam gear installed correct with the correct lenth pin, if not the pin cound let the cam gear slip and be off time.
    Is the exhaust cloged up, do you run Cats or maybe a crushed pipe or muffler.

    Does the explorer cam have the same firing order as the old cam, maybe spark plug wires on wrong
  4. mustangman1974

    mustangman1974 Member

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    ok its not been out of my car since I purchased the crate engine fro Ford. I found out this month that the cam was replaced by the rebuilders at Ford when they saw the california shipping address. Took them 2 years to finally tell me that it was supposed to be a Cobra replacement motor. At least it has roller rockers.

    I installed the timing chain and its straight up. I did not advance or retard the cam timing.

    Water flow - to good- pushed the lower spring into the upper part of the radiator and pulled the lower spring almost into the water pump.

    Radiator is a fluidyne 3 core alu. radiator with mechanical shrouded fan pulling and a spal 14in pusher.

    Compression is about 165-168 in all cylinders.
  5. TOM B

    TOM B New Member

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    Running a thermostat, do not run without one as the engine will just keep getting hotter because the coolant dont have time to cool off in the rad.
    head gaskets on correct, SBF gaskets only go on one way or it will over heat.
  6. mustangman1974

    mustangman1974 Member

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    done at rebuild. Engine ran warm when I installed it but rarely over 220 in traffic and 110 heat. Which was to be expected. I picked up a 180 degree thermosdadt and plan on drilling a 1/8 hole for flow. I am also just for kicks going to install some cheapie ignition wires. I found a prior post where wires caused temperamental problems.
  7. rbohm

    rbohm Founding Member

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    with the fact that your motor starts breaking up when the engine temps climb, and is getting worse in hot weather, tells me that you have a fuel system issue. make sure your float level is set properly, and check the routing of the fuel lines to make sure there are no hot spots any where that might be causing vapor lock. check your fuel lines for evidence of clogging. if all else fails try installing an electric fuel pump near the tank and see if that cures the problem. what you are describing is a classis case of a lean fuel mixture.
  8. mustangman1974

    mustangman1974 Member

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    here is something new. Last night about midnight I found a post about checking wires. Well off to the garage with my mister. Well I noticed some of the wires had some archs. Kind of sucks because they are for motor sports and not even 9 months old. I replaced the wires and the problem is still there.
  9. BarnStang

    BarnStang Founding Member

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    It's unlikly, but the coil could be breaking down when it gets warmed up. Even if it's new. If you run out of things to check, you could try swapping that out. Hmmm, looked over the Mallory site. Seems like a pretty tight ign system. Check what the Mallory instructions say to gap the plugs at for that ign system and double check that. I put a Jacobs system in my 93 5.0 and the inst were very explicite about setting the gap right. Also, you could also check what plugs Mallory says to run with that ign sys too. Seems like I had to run a different heat range than stock, but that may have been the alum heads so not sure if I remember that correctly or not...
  10. bnickel

    bnickel Founding Member

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    try a phenolic spacer under the carb, even a very short 1/8" one will help with vapor lock. also try running a mr gasket or robert shaw high flow t-stat, it will help eliminate hot spots. also try advaning the timing to 12-14 degrees at idle and a total of 36-38 all in.

    if your distributor has a vacuum advance you could try adjusting it as well, if you don't have a vacuum advance you might consider getting a dizzy that does have one.
  11. STSFCTN67

    STSFCTN67 New Member

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    updates?

    Did you fix it? We need to know what worked.
  12. S-Car-Go

    S-Car-Go Member

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    Did this happen all of a sudden or gradually? With 34k miles, I’d guess it’s been to 200* without problems plenty of times in the past. How long has it been since a tune up? What do the plugs look like? Inside of the distributor cap? Probably not ignition, but best to rule out things like a cracked cap, plugs that are on the edge, etc.
  13. oz

    oz Founding Member

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    Electrical resistance goes up with temperature so if you have a sketchy coil or module, it would act up when it gets hot. The Accel on my '91 was weak and would cut out and then not fire the car until it cooled. I had Accel rebuild it and it's fine now.

    I have a Edelbrock 1405 and performer rpm intake on my 302 without spacer and have never had any problems when the engine is hot.
  14. other_shoe

    other_shoe Member

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    x2 on not ruling out the coil.

    I had what sounds like the same problem about 13 years ago and it went away after I replaced the coil.
  15. mustangman1974

    mustangman1974 Member

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    well I did some changes I rerouted my fuel lines, help a little. I had an 02 bung welded in tuesday and hooked up a lm-1 wideband a/f sensor.

    At idle it is bounces from 12.5-13.5. However, load the engine up and it jumps to to one it jumps 15-17.1. - Would this indicate metering springs?

    However after the quake the trains stopped and I got stuck, did its lake of power thing in neutral, and had to shut the car down. The temp creaped over 220 and that makes me nervous. No boil over however I did notice when I looked in glass fuel filter there was bubbles streaming up from the fuel pump side of the fuel filter. slowly and surely the filter became empty.

    Still working on it. Kind of sucks I have to wait a day to try it out. I work on it in the evening so I can touch my tools, but then have to wait until the next day to test it out int he heat of the day. I have 4 days to fix this thing I go back to work on tuesday.
  16. rbohm

    rbohm Founding Member

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    i think you have a serious fuel supply issue. i suggest installing an electric fuel pump near the tank, and see if that solves your problem.
  17. oz

    oz Founding Member

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    Oh G0D, your A/F mix is not right!
    You should be around 15:1 at idle and drop (richen) to ~11.5-12.5:1 at WOT. Start by changing your secondary metering rods and/or seats to something much bigger (smaller rod and/or bigger seat). Do you have the carb metering kit from Edelbrock? It has all the different rods, seats, vacuum springs, etc that you'll need. The mixture combination chart is in the owners manual. You need to try a combo that richens WOT. Once you're close, you can go back and tweak idle and part throttle mixture (main metering circuit and vacuum springs)

    A lean burn will cause excess heat as well. I wouldn't be surprised if your exhaust is glowing with a 17:1 mix. You could damage your pistons too if you're not careful (very hot combustion).


    BTW - where did you get your A/F meter? I installed bungs but need to beg/borrow/steal a meter to tune up my car properly.
  18. mustangman1974

    mustangman1974 Member

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    a friend has an innovative lm1 data logger. I gives real time 02 readings. I made one with a narrow band o2 meter using lm3914s its just as accurate from about 13-16.1 outside of that its just a light show.

    I did notice one of my power steering hoses is no touching the fuel going to the carb.

    I am going to change the metering springs to 7s. Is there a better way to select the springs besides trial in error?
  19. ForceFed70

    ForceFed70 That's why they call it "dope" Founding Member

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    Double check your ignition timing. AFR readings are not the holy grail... things like bad timing can effect them.

    If your igniton timing is good (check at idle, and at RPM to make sure your advances are working). Then I would look into the fuel system.

    13:1 at idle is fine. But under load you should be at 14:1 or lower.
  20. mustangman1974

    mustangman1974 Member

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    I messed with the fuel hoses more and noticed the bogging has lessoned. I can assume its a fuel problem now, or at least I think.

    I purchased some new an fittings for the fuel pump in hopes I can route the fuel hose away from everything hot.

    One question though, with and edlebrock fuel pump. Can you use the bottom feeder plate for just one port, or are you stuck using both? There brilliant engineers placed the inlet for the fuel pump right against the oil filter, only 1/2 inch clearance.

    Another piece of evidence. I took all the plugs out, all brand new or about 100 miles on them. I noticed they have are all mostly white. or a fine white powder on them. Except number 2. The electrode looked normal, but the threads and cavity of the plug were coated in soot. I might even say oil, but it does not look like the examples I have seen for oil deposits, but definitely darker/wetter then soot.

    Could this be my vaccine leak? Maybe sucking oil from under the intake, which is why I haven't found the damn thing?

    Would this make idle run rich and load lean out?

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