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Back to the drawing board! wont run
Posted: Fri Dec 05, 2008 4:33 pm
by Wayne64
When I first got the M37B1 I thought I had a fuel problem as it would idle rough and as soon as you touched the throttle it stalled. The gas tank was loaded with water, so I have rebuilt the carb and installed a lower pressure Facet pump. I tried it today using my boat 6 gal. tank with fresh fuel and the same thing is happening? If this is any hint when it starts at 35 degrees it will do so with no choke applied, idle rough for a while and die. Any suggestions folks where to continue testing?
back to the drawing board
Posted: Sat Dec 06, 2008 4:33 am
by vinkon3775
sounds like to much fuel. when you had the carb apart did you correctly set the float height? how much fuel pressure do you have?
Posted: Sat Dec 06, 2008 5:31 am
by Wayne64
It could be the carburetor but I doubt it. Even though it starts with no choke and no air cleaner which does point to excess fuel at cranking and the rough idle. The float level is correct and the reason I went for a new electric pump was that the one that was there was a Carter which I know was pushing to much PSI. My neighbor has the same Carter on his big block powered F-100 and after having trouble with getting his Holleys bowl level right he added a gauge and then a regulator to get the PSI down. The Facet I used pushes 2-1/2--4-1/2 psi. When it warms up I'll pull a few plugs.
Posted: Sat Dec 06, 2008 6:00 am
by VROD02
Double check your points. Always seems to be my issue. My 1st 37 was doing simular things as yours and it was dirty points.My 715 idle great rev without a miss. cut out with a load. Freakin points!! If I only owned one truck I'd spend the money on the electronic kit.
Posted: Sat Dec 06, 2008 7:14 pm
by MSeriesRebuild
You mentioned a 2 1/2 to 4 1/2 PSI pump pressure rating. Around 4 PSI does a good job if the pump is furnishing enough volume. Correct fuel volume is just as important as correct PSI. Too much PSI will overwhelm the needle valve causing flooding as you already know. Too little volume at any PSI rate will cause starvation. Could well be a timing issue or electrical issue also, check out everything. Correct timing setting is 4 degrees BEFORE TDC.
Posted: Sat Dec 06, 2008 7:55 pm
by Wayne64
Sorry Guy's but I thought I posted what I found earlier in the day. A very weak spark while cranking and the plugs are black. So next week when it's a bit warmer I'll pull the "igniter". Thanks Charles in referencing the 4*BTDC, lucky for me I bought the full electrical test kit a few years ago while working on Military 10KW generators.
Posted: Sun Dec 07, 2008 7:05 am
by topellis
Wayne,
From your original post, something I would at least check is that the choke isn't on at least some.... all the time. I know that this caused a stalling like hesitation when I would press the gas. It has been so long ago since I did it I can't remember how I did it but Charles is who told me how to do it I think. It was like the choke was on a little all the time and you said you never have to use the choke... just something to check. Think the original carbs just run rich, not sure why it was designed that way but I have heard many people say it was just the way they were.
Good luck and keep us posted.
Mark
Posted: Sun Dec 07, 2008 1:48 pm
by MSeriesRebuild
A weak spark will cause it to appear to be running rich, soot on the plugs, etc. Many times problems in the distributor are mistaken for or thought to be carb issues. Weak compression will show up the same symptoms sometimes. Weak spark is often caused by a coil on its way down, bad ignition lead filter capacitor, corroded/burned points, bad distributor cap & or rotor, loose shaft/bushings, worn shaft cam, bad plug cables, etc. Lots of little issues can combine to roll out real problems, check it all.
Posted: Sun Dec 07, 2008 1:53 pm
by VROD02
I'll take points for 500 Alex.
