Tekira Posted December 21, 2005 Share Posted December 21, 2005 Hi, I have had this problem for about 4 weeks now and it has been getting worse. I have been driving my car to work lately (25 Miles). When i start the car up it runs fine, smells bad though, then i take it on the freeway and it crusies just fine. Then when i stop at the gas station to put in some gas and the car sits for about 5 min i start her up and the idle is rough and then my missfire problem starts as soon as i start to drive. And its REAL bad. It cuts out completly almost like its running out of gas. kinda like mrrrrrrrrr pop pop mrrRRRRRRRR pop MRRRRRRR. It seams to lessen when i floor it. But Between 10% And 50% throttle Its horrible. The problem gets even worse as the car sits in traffic and heats up, It just lets out a big pop fom the carbs and craps out. This is just like when my coil went out. When i would sit in traffic the coil would heat up and cause missfire. But let me list what i have allready replaced or done to the car to try to fix this: NEW Coil, Wires, cap and rotor, NGK spark plugs, fuel filters, Voltage regulator, Battery Holly Blue fuel pump set to 4 psi, ALL new fuel lines, Su carbs taken apart and cleaned, set timing and set correct rotor phasing What iam try to say is its getting pleanty of fuel and i have replaced all ignition components EXCEPT my crane cams xr-3000 ign unit. Iam thinking that may be the problem but i JUST installed it about 6 months ago. Also i looked at my spark plugs and the tips and the insulators are white. The Car smells bad like its rich though? Because this only happens after i get the car good and hot means something is failing due to heat. Could it be the valves. I just adjusted them 5 months ago. and it only started doing this 4 weeks ago. Also when i down shift into 4th when i am getting off the freeway it pops and back fires like a mofo. I hope i have given u guys enough info to help me out. My car specs are in my signature. I am about to shoot my self over this one:cry2: Quote Link to comment Share on other sites More sharing options...
EZ-E Posted December 21, 2005 Share Posted December 21, 2005 Well first let me say this, if you are getting a backfire through the carbs, that usually indicates a lean condition. Second, what are your plugs telling you? Are they carbon fouled, white and burning hot? Do you smell fuel on them? Your plugs will tell you a lot of how your car is running, I would start there to find out what is causing your problem first, before throwing money at it. It will save you a headache and also keep your pockets a bit heavier. Quote Link to comment Share on other sites More sharing options...
Tekira Posted December 21, 2005 Author Share Posted December 21, 2005 In my post i said the plug tips and insulators are white and dont smell like gas. They look almost new. Quote Link to comment Share on other sites More sharing options...
Tekira Posted December 22, 2005 Author Share Posted December 22, 2005 Well i cleaned out the carbs again, hooked up my colour-tune and got the carbs good and tuned up, they were a little lean, but i have had them tuned that way before with no probs. And i Ordered a new xr-3000 unit and a 160 deg thermostat. When i touched the unit its was very hot. I will also check and adjust my valves again. A little side note: 20w50 does not make good carb damping oil Iam starting to think its worth it to just buy the malory dual point dist and just get rid of electric ign control. Quote Link to comment Share on other sites More sharing options...
Tekira Posted December 29, 2005 Author Share Posted December 29, 2005 Well i installed the new xr-3000 and that wasent the problem. The thermostat helps. All my plugs were white and hot, lean. Then coming home it started cuting out on me going up hills or when i gassed it. I look at the clear fuel filter comming from the tank and it barley had any fuel in it when the car was running. The pump was sucking air half the time causing the overly lean condition. I have been pulling gas from the drain plug because of a bad tank so i decided so swap out the tank with one i got that was in better shape. I put in the new tank and jumped up the fuel regulator to 4.5 psi and adjusted all valves. Took her out for a test drive and floored it in 3rd and it went all the way up to 5500 rpms with no starvation. (It would crap out before). It also stoped missfiring. It still does missfire a little when it gets a little to hot but not as bad. Did the head or valves get ruined from running it so lean for so long. Also When i put ATF in for damping oil the missfire was as bad as it was before Anyone??? Quote Link to comment Share on other sites More sharing options...
280zwitha383 Posted January 9, 2006 Share Posted January 9, 2006 vapor lock? Quote Link to comment Share on other sites More sharing options...
v80z Posted January 10, 2006 Share Posted January 10, 2006 coils and plug wires will exhibit these symptoms. At first statup and for the first 15 minutes, or until car gets warm, everything is fine. Then idle and cruis is fine but try to accelerate and stumble pop. Wires are the least expensive then the coil. Replace. Quote Link to comment Share on other sites More sharing options...
JMortensen Posted January 10, 2006 Share Posted January 10, 2006 Being that this is a 74 and they're notorious for vapor lock, and this problem presents when the car has been sitting in traffic, I'm going to say that you might want to look at that possibility. I'll tell you what I did to eliminate vapor lock when I was running SU's': I ran an electric pump back by the tank. I ditched the mechanical fuel pump and the stock fuel rail. The fuel pump gets HOT, and the rail is bolted to the head, so even if it has that heat wrap on it it's still bolted the the head. Not good. I ran a rubber fuel line from the filter across the radiator support and back to the carbs. I had it "dead headed" so there were no return lines. This will wear out your fuel pump faster, but it is easier to plumb. That was basically it. I only had vapor lock on my 70 one time when it was 105º at the track, but I never had it again after that. You might also look at improving on the stock heat shield for the exhaust manifold. Quote Link to comment Share on other sites More sharing options...
BrandonsZ Posted January 10, 2006 Share Posted January 10, 2006 I'm running a carter 16psi pump in the back pushing through the stock lines and regulated post filter to 6psi. Then another set of twin parallel filters (clear) to the carb. Edelbrock Avenger AVS wanted 5.5psi, I regulated it and it did starve twice in 1000miles only when pushing and only after sitting in traffic a while and on less than 1/2 tank, I turned it up to 6psi at the reg and it hasn't done it since. Also after I turned it up was the only time I ever saw fuel in those clear filters, I always thought it was odd that I never saw any fuel in them while my truck has a mechanical pump and the filter is always full with fuel? Still don't understand it but now the filters have fuel. Go figure. Turn it up a little more your gage on your regulator may be reading low (uncalibrated). Quote Link to comment Share on other sites More sharing options...
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