Two issues I have ?'s about.

peter e mark · Post by **peter e mark** » Thu Jul 09, 2009 6:23 pm

Hello everyone, And I did experience this very same problem with " vapor lock" when I bought my 19 and 52 M37..I first installed a vacuum gauge on the fuel line close to the carb, and upstream of the aftermarket in line filter. If you would like to see a picture of this setup, please e-mail me as I don;t know how to upload on this sight. What I saw on the guage was a poor suction pressure , something less than what the book says is the delivery pressure of the fuel pump, whiuch is 4.5 PSIG I replaced the fuel pump. No help. Then I replaced the fuel tank filter. While it looked dirty, it was No help. THEN I REPLACEd THE ENTIRE GAS LINE, from tank to carb, yes, the entire line. and whamo, the fuel pressure on my gauge was good and consistant, and no more " vapor lock". That's because it wasn't vapor lock, it was a clogged gas line combined with leaks in the gas line fittings used to jump out the original fire wall mounted fuel filter. Thge gauge read low because of the leaks, but the pump also could not deliver because of the restriction. If it was only a restriction, the guage would have read higher than 5 psig, if only leaks it would have read low all the time. The combination of the two problems made the guage useless but what I did worked and with my 4:89's I drive at highway speed for hours without a problem. Don't play with it. Re fit your entire fuel system and drive yopur machine with confidence....Peter Mark

knattrass · Post by **knattrass** » Fri Jul 10, 2009 1:53 am

For once the Long Island Wonder might be on to something.....years of water in the tank and condensation on the steel lines can easily close up otherwise good looking gas lines. Just for grins, we saw-all'd thru ours and they were almost rusted shut in some of the tight bends - nothing you could see from just looking at them. JB has a nice kit all pre-bent ready to go. Worth looking into. Keith

Nickathome · Post by **Nickathome** » Fri Jul 10, 2009 2:33 am

wvcharlie wrote:What condition is your motor in? My motor was running fine although it was pretty tired and burned oil. Then I started having trouble with vapor lock. I tried everything to try to cure it, but nothing worked. At the same time I noticed my oil pressure was a little lower. Then all of a sudden, I had a rod bearing go bad and that pretty much ruined the motor. I didn't realize it until it was too late, the probable reason for the vapor lock was that rod bearing was going bad and letting oil blow by and reducing the oil pressure, which in turn was reducing the cooling ability. This made the motor run hotter which caused the vapor lock. This may all be irrelevant for you if your motor is in good condition, but I wish I would have caught my problem sooner. Now I am in the process of replacing the motor.

Not being a mechanic I can't say for sure the condition of my motor, other than it runs well. Is it tired, I'd say yes? Have I had it rebuilt, no, can't afford to at the moment. I only seem to have vapor lock when the temps are warm. I have not noticed a difference in my engine's running temperature, and oil pressure but I will definitely keep an eye on things.

Nickathome · Post by **Nickathome** » Fri Jul 10, 2009 2:38 am

MSeriesRebuild wrote:All sorts of issues could be in play, if you haven't run a compression check, by all means do so. It will answer several questions & really get you in the know concerning engine condition. It will either let you know serious concerns are lurking or give you real peace of mind that your engine is good to go. Only takes a few minutes to do it.

I did do a compression check on my engine a few years ago. Mind you I had never performed such an operation in my life before that so when I was finished the readings I got(or at least thought I got) seemed to be too low for an engine to be able to run from what I remember people telling me. I remember the readings being something in the 70's PSI range, and from what everybody told me at the time, there was no way my engine could be running well with those kinds of readings, so I could only conclude that my test was flawed, most likely operator error. I know I had to have done something wrong, or maybe the tester I bought is junk. I will have to read up on the subject and conduct another test.

Nickathome · Post by **Nickathome** » Fri Jul 10, 2009 3:02 am

peter e mark wrote:Hello everyone, And I did experience this very same problem with " vapor lock" when I bought my 19 and 52 M37..I first installed a vacuum gauge on the fuel line close to the carb, and upstream of the aftermarket in line filter. If you would like to see a picture of this setup, please e-mail me as I don;t know how to upload on this sight. What I saw on the guage was a poor suction pressure , something less than what the book says is the delivery pressure of the fuel pump, whiuch is 4.5 PSIG I replaced the fuel pump. No help. Then I replaced the fuel tank filter. While it looked dirty, it was No help. THEN I REPLACEd THE ENTIRE GAS LINE, from tank to carb, yes, the entire line. and whamo, the fuel pressure on my gauge was good and consistant, and no more " vapor lock". That's because it wasn't vapor lock, it was a clogged gas line combined with leaks in the gas line fittings used to jump out the original fire wall mounted fuel filter. Thge gauge read low because of the leaks, but the pump also could not deliver because of the restriction. If it was only a restriction, the guage would have read higher than 5 psig, if only leaks it would have read low all the time. The combination of the two problems made the guage useless but what I did worked and with my 4:89's I drive at highway speed for hours without a problem. Don't play with it. Re fit your entire fuel system and drive yopur machine with confidence....Peter Mark

This may be my probelm, as twice now I have noticed rust particles in my fuel filter. At some point I am going to have to replace my fuel lines. Its finding the time that is the problem. I got more projects going than Carter has liver pills at the moment.

HingsingM37 · Post by **HingsingM37** » Fri Jul 10, 2009 3:27 am

Nick,
It looks like your fuel pump could get pretty hot there as you have the industrial version engine. I have an actual Chrysler Industrial manual and several of the manifolds shown exhaust up away from the fuel pump such as welder applications. Your engine in the truck application may experience more heat build up near that fuel pump. You may want to consider an electric fuel pump mounted in the rear when you replace your fuel lines.

Nickathome · Post by **Nickathome** » Fri Jul 10, 2009 5:23 am

HingsingM37 wrote:Nick,
It looks like your fuel pump could get pretty hot there as you have the industrial version engine. I have an actual Chrysler Industrial manual and several of the manifolds shown exhaust up away from the fuel pump such as welder applications. Your engine in the truck application may experience more heat build up near that fuel pump. You may want to consider an electric fuel pump mounted in the rear when you replace your fuel lines.

David;

My truck already has an electric fuel pump. I thought I was having problems with the pump overpowering the float needle and causing excess fuel to dump into the carb. I was getting a gas smell in my oil as a result. So, I installed the mechanical pump which did solve that issue but caused the vapor problem as a result. Again its only when its real warm do i have this issue.

Post by **T. Highway** » Fri Jul 10, 2009 7:47 am

Whenever I put an electric fuel pump on a carburated gas vehicle I would add a regulator so that I could dial down to about 5 PSI and not overwhelm the float.

MSeriesRebuild · Post by **MSeriesRebuild** » Fri Jul 10, 2009 8:47 am

4 psi is good for an electric pump, works great without a regulator. This would be a good idea in your case & should prevent vapor lock once & for all.

Concerning the compression test results, 70 is LOW & unacceptable, but it isn't unheard of for an engine to run with poor performance like that, however issues will arise similar to vapor lock in hot weather. I have one here right now with complaints of stalling issues. After a test revealed some readings of 40's/50's, we gave up on doing anything else simply because it's fruitless until the engine is overhauled.

You mentioned a possible flawed test, I'd say run another known correct test to verify the real results. If it's low, so be it, in all honesty if the situation is such that it needs a rebuild, there is no need in spending any money on other solutions that will not be worth anything until the low compression issues are dealt with. Not trying to pop your bubble, these are just simple facts. If the second test proves a better result verifying the first test as flawed, then you can look further into other repair options. Actually if the test result is 100PSI, even that is not good at all. If readings are lower than 100, forget it & start saving for a much needed rebuild, anything less will be of no use at this time. I know how you feel, but there comes a time where nothing else works except facing the facts & attending to issues at hand.

peter e mark · Post by **peter e mark** » Sat Aug 08, 2009 6:45 am

Logical intelegent and otherwise creative thinking is certainly required in situations like this one. Time tested , safe and otherwise mechanically proven procedures are what we all aspire too !And all of the conributors gave important insight into addressing this vapor lock problem, but the guy who confessed to cutting his gas line with a sawzall ! ...KNATTRASS, you've been inhaling too much vapor from that high tech polish you use; wear a mask , hold your breadth, or use oxygen...

Two issues I have ?'s about.

Re: vapor lock