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Fuel Starvation
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Author:  Bruce [ Sat Jan 03, 2015 4:27 am ]
Post subject:  Fuel Starvation
I live in central Florida and have a 83 Dodge D150 slant six that I have 1945 carb on and the lean burn removed.

It will start immediately anytime during the day (with no pumping) once it has gone through its morning starting ritual.

But the 1st start of the day takes turning the engine over for a couple of minutes, then pumping the throttle several time and then it will start. Its only first start of the day that it takes this and I believe it is clearly fuel not choke related.

I don't believe this is fuel line boiling because it doesn't do it after a good drive and it sits.

I also put a check valve on the fuel at the carb thinking it was fuel drain back from the bowl but that didn't seem to effect anything.

So what am I missing?
Author:  nm9stheham [ Sat Jan 03, 2015 7:26 am ]
Post subject: 
I would pour a thimble full of gas down the carb 1st thing to see if it fires off for a few rotations, to eliminate it being something besides the fuel delilvery. And look down the carb throat and see if it pumps out any fuel. But you may have done these thigns already since you suspect the fuel delivery.

Then check the fuel pressure while cranking cold; this sounds most likely to be a bad fuel pump. There are check valves inside the pump at inlet and outlet, and either one bad would do this. And perhaps the pump's lever is sticking, or has a weak or partially broken spring.


Once it is running, does it run OK at highway and interstate speeds?
Author:  SlantSixDan [ Sat Jan 03, 2015 7:32 pm ]
Post subject:  Re: Fuel Starvation
Quote:
I live in central Florida and have a 83 Dodge D150 slant six that I have 1945 carb on and the lean burn removed.
How careful/complete of a job was done in removing the Lean Burn? Did you keep the Lean Burn carburetor, or swap on a conventional carb?
Quote:
It will start immediately anytime during the day (with no pumping) once it has gone through its morning starting ritual.
Your difficulty could be leaky fuel pump valves (try a new fuel pump) and/or a pinhole air leak somewhere between the fuel tank and the fuel pump allowing the fuel to drain alllllllllllllllllllllllllll the way back to the tank overnight.
Quote:
I also put a check valve on the fuel at the carb
Interesting...can you show us a link to the check valve you installed?
Author:  Bruce [ Tue Jan 06, 2015 3:54 am ]
Post subject: 
Thanks for the replies, sorry for the delay in getting back with you.

The fuel pump is a real possibility. I replaced it when I removed the lean burn with one from Advanced Auto (don't remember who the manufacture was.)

I did the lean burn myself and right. However the carb is a different story. I played around for a month with 3 different rebuilt 1920 (2 I did myself) and it ran horrible! Then I rebuilt the 1945 lean burn that came on the truck (1983) just because I had the carb and a kit laying around, bolted it on and it ran great - except I hoped for better mileage.

When I first put the fuel pump on with the 1945 it would start right up (even without the choke). But after a couple months it began starting hard first start of the day.

I'm a little scared to post a picture of the check valve because I know that I will be able to hear you laugh here in Florida. All I can say is, desperation causes people to do crazy things. Its milk bottle nylon, about a 1.5" long, 1/4" inlet/outlet and the valve portion is about the size of a dime and a 1/4" thick. It cost me a $3.50 off Ebay. No it didn't help and I believe it caused me to starve for fuel at 50 mph (prior to the valve it would run fine at highway speeds). I just put it on and it comes off today before I take the truck to the alignment shop.

While were on the subject let me ask about mileage. I get about 15 mpg. around town. Its a lwb d150, the engine is tired, probably 200K, and I'm guessing it got pretty short rear gears because it tops out about 70 mph.

Any idea what I should expect all things being equal?

Thanks Bruce
Author:  Reed [ Tue Jan 06, 2015 4:12 am ]
Post subject: 
15 mpg in town driving in a slant powered truck is pretty good.
Author:  nm9stheham [ Tue Jan 06, 2015 10:07 am ]
Post subject: 
Yep, you are pushing that weight up to speed every time you move out, and the 15 mpg would be very believeable with short gears, worn engine, etc. Just the power used to run your 'internally powered air pump with auxiliary output shaft' (aka, engine) is non-trivial with the amount of displacement.

BTW, crud in the old fuel tank can be causing the check valves in the pump to hang open or get damaged. So, keep that in the back of your mind even if you change the fuel pump out and it cures the issue.
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