Possible fuel problem.

Wes · Post by **Wes** » Mon Jul 20, 2009 4:31 pm

Here's the situation. I drove my M37 out to my hunting camp. The first leg of the trip was about 20 miles of 2 lane highway driving at about 40-45MPH with some hills. I turned onto a dirt road the went to camp and stoped for a short break but left the engine idle. After 5 minutes I got back in to go. I made it about 30 yards then then the motor started balking. I pumped the gas hoping to prevent it from stalling but it had no effect and the motor died. I tried restarting and it would fire but again the gas pedal seemed to have no effect and it died again. After that it wouldn't even fire. I got a tow the rest of the way to my cabin. As we were pulling down the last road I droped the clutch and with the pull start it started and made the last 1/4 mile under it's own power. Again, I lft it idel to carge the batteries then shut it off as it was time to head home in another vehicle. The next day I went out to camp and It started right up. I drove it about 3 miles on dirt road and the same thing happened. I got my Tahoe and pulled it back to camp. I tried again to pull start but it no luck. I pulled out the fuel filter and it had a little dirt bit not very bad. It sat for about 2 hour and I tried to start it but not go. This looks like a fuel problem any advice?

DJ · Post by DJ » Mon Jul 20, 2009 6:18 pm

I would check for spark when it quits when warmed up, sounds like the coil could be your culprit. It gets hot and quits working.

Lifer · Post by **Lifer** » Tue Jul 21, 2009 3:20 am

I'll second DJ's motion.

8543bob · Post by **8543bob** » Tue Jul 21, 2009 3:35 am

I HAD A VERY SIMILAR PROBLEM. FOUND A RUBBER FUEL LINE HAD COLAPSED AND RESTRICTED THE FLOW. NOT ALL THE TIME BUT LIKE YOURS COULD START AND THEN STALL. THE LINE IN QUESTION WAS JUST AFTER THE FUEL SHUT OFF VALVE IN THE ENGINE COMPARTMENT. INSTALLED A NEW LINE, THAT IS NOT EFFECTED BY ALCOHOL AND ALL IS WELL SINCE
GOOD LUCK

tmbrwolf · Post by **tmbrwolf** » Tue Jul 21, 2009 5:54 am

I'll third the coil and add, Is the heat shield missing from the fuel pump or a fuel line routed close to the exhaust manifold? Could be vapor lock, after sitting at idle there isn't much air flow under the hood and things could be getting a bit hot, Check for spark if that is present, check for fuel at the carb!

knattrass · Post by **knattrass** » Tue Jul 21, 2009 8:27 am

I could have written the same posting here recently. Been driving all over last year never a problem. This year M-Day, noticed a drop in idle rpm and figured I would put the timing light on it. On the way home, it died at a light and wouldn't restart. Same thing on a pull home, I did a 3rd gear braking on the tow vehicle and decided to throw the ign switch. It fired right up (was sitting for 20 mins waiting for tow) and drove home the rest of the way. Sunday went about 4 miles, stopped, drove some kids around the block for a few, stopped. When I went to drive off, it started to sputter like it took a load of water. Pumping the pedal kept it running barely and then it cleared. 50 feet later same thing. Would start to stumble driving at 35mph and then clear. Will check fuel this weekend but I've topped off the tank since storage and been using the truck on short runs. I thought coil since it was intermittant when warm and not firing up right away when warm. Charles also recommended a compression check. Let me know if you find a replacement coil (and where). Thanks! Keith

monkeymissile · Post by **monkeymissile** » Tue Jul 21, 2009 9:52 am

Unless you have an alternator I don't think the batteries charge much (or at all) at idle with the original generator.

Lifer · Post by **Lifer** » Tue Jul 21, 2009 6:57 pm

monkeymissile wrote:Unless you have an alternator I don't think the batteries charge much (or at all) at idle with the original generator.

A DC generator puts out current whenever it's turning. How much of that current gets to the batteries depends upon the voltage regulator. An AC alternator, on the other hand, does not put out much (if at all) at an idle. Alternators usually have to "come up to speed" before providing a usable output.

monkeymissile · Post by **monkeymissile** » Wed Jul 22, 2009 8:12 am

Lifer wrote:
monkeymissile wrote:Unless you have an alternator I don't think the batteries charge much (or at all) at idle with the original generator.
A DC generator puts out current whenever it's turning. How much of that current gets to the batteries depends upon the voltage regulator. An AC alternator, on the other hand, does not put out much (if at all) at an idle. Alternators usually have to "come up to speed" before providing a usable output.

oops, guess I got my info incorrect. Thanks!

N1VSM · Post by **N1VSM** » Wed Jul 22, 2009 8:14 am

Lifer wrote:
monkeymissile wrote:Unless you have an alternator I don't think the batteries charge much (or at all) at idle with the original generator.
A DC generator puts out current whenever it's turning. How much of that current gets to the batteries depends upon the voltage regulator. An AC alternator, on the other hand, does not put out much (if at all) at an idle. Alternators usually have to "come up to speed" before providing a usable output.

Isn't it the other way around? The generator's output (current) is determined by the rotational speed. Low RPM = low current. Alternators are self-generating. You do need to give them a "goose" to get them going, but after that they are up & running.

Lifer · Post by **Lifer** » Wed Jul 22, 2009 8:20 am

With a generator, low rpm = low current output, but there is still a current flow. With an alternator, you won't get any current flow until you "goose" it a bit. This activates the internal voltage regulator, allowing current to flow, but you have to keep the rpm up above normal idle speed. With newer engines, this isn't a problem, but our engines idle well below the "stall speed" of modern engines.

monkeymissile · Post by **monkeymissile** » Wed Jul 22, 2009 8:43 am

checked out this link (http://www.rowand.net/Shop/Tech/Alterna ... Theory.htm) and more specifically this line......

"The voltage of the generator is controlled by the number of windings in the armature. The current output varies widely from zero if the battery is perfectly charged and nothing is using any power up to the maximum rated output of the generator. The current output is controlled by the field current, but also by the speed at which the armature is spinning. This is important because a generator can only put out it's maximum rated current at or above some speed - at lower speeds the output drops off very quickly. This is why a generator-equipped car will not charge (or even maintain!) the battery at idle and this is one of the main reasons for the development of the alternator."

Possible fuel problem.

Possible fuel problem.

fuel lines

FYI

Re: FYI

Re: FYI

Re: FYI

I did a little research....