Frustrating Acceleration Problem

[eaglevets]

I have an otherwise great-running MUTT. At times she will lose power when accelerating. Usually happens above 40 mph. As you give it gas, it chokes and coughs and tries to shut down. Ease back the gas to 30 to 35, and it chugs along. This is an intermittent problem, but is quite troubling, since it can happen anywhere without warning (usually on an incline). We cleaned the gas tank and fuel lines and insulated the lines (thinking a vapor problem). Put in a new fuel pump (the Chevy conversion), but still don't have a solution. What say you? Ever had this problem?

 

[101coolcars]

I've had mica in the fuel system "filter" that cause problems like your having. The little platelets pack up against the filter but then lay back down allowing flow from time to time. I think the mica comes from contaiminated fuel stations especially in the mountains or rural areas.

 

[NDT]

Are you running with the choke half out? That usually solves this.

 

[Coffey1]

Float in carburetor could be acting up.

 

[eaglevets]

Has anyone had any luck with a fuel additive?

 

[Jeepsinker]

Accelerator pump in good shape?

In carbureted vehicles, the only additive I've ever had luck with was Seafoam, or Berryman's B12 chemtool.

 

[uriss]

For all my vehicles I have put inline a regular boat water separating fuel filter. Readily available as a kit from Wal-marts for around twenty dollars. Live right on the river and I drive older vehicles with crud in the tanks. Spin a filter off and spin a fresh one on. Takes care of my problems all the time.

 

[Jeepsinker]

That is a good idea. Any fuel filter is better than none.

 

[m38inmaine]

The M151 is famous for a flat spot in the carb, the TM shows pulling the choke out until it smooth's out then loosen the cable clamp on the carb, push the choke cable back in and re tighten the clamp screw. There is a company in Florida called Brooks Engine Service that fixes this problem, they advertise is MVM.

 

[eaglevets]

Some great feedback - thanks, all. A friend uses AVGAS in his - contains lead, not ethanol. He says that gets rid of a lot of the problem for him.

 

[nattieleather]

I would always run my M151 on the hi octane gas 93 or better if I could find it so the Avgas would be the same thing. If I put the old 87 octane in I would have the problems you are talking about.

 

[Westech]

Double on the 91/93 octane fuel. Make sure there is NO ethanol in the fuel.
Also change out the intank and inline fuel filters.

 

[eaglevets]

Roger on the fuel. Thanks!!

 

[Bill Nutting]

Oh boy did we have this problem! First off, get your carb " rebuilt" by Brooks Engin Service. Then try to improve your fuel. We mix a gallon or two of racing fuel to a tank of the junk they sell as "gasoline" these days. These old vehicles just don't run right on alcohol. This stuff boils at a lower temp than real gasoline causing vapor lock. You may also try a "lead additive" in your gas. I have been running my M37 on modern fuel for 11 years. In the last two years I have been having vapor lock issues. Adding a little racing fuel fixes it for me. Our M151 runs a lot better since we had Brooks do the carb. It runs like a top with the chock wide open. Down side to racing fuel is it costs $8.00 per gal. It's the same gas we used to buy for 25 cents a gal. in the 60's...

 

[eaglevets]

All great ideas. We've done many off the things you suggested and Monday will replace the carb. I shall not be defeated!!!

 

[eaglevets]

Well, we put a new carb in it and it runs good. Except, now it is slow to start. The starter turns for a good 60 second plus, before there is fire in the hole. Thoughts?

 

[dmetalmiki]

Float drain back? I had this problem (long cranking)the fuel goes back to the tank!. Put a one way valve in. Cured.

 

[eaglevets]

Where di you get your back flow prevention valve (that's what we call them in utilities). Do you have a mfr and p/n, too? Thanks!!

 

[eaglevets]

We're not through with this yet. Still starting issues. Replaced plugs and batteries. Replaced coil (twice). Cleaned out distributor and contacts. The starter turns with much vigor, but the system won't fire for a good minute of turning episodes, it it fires at all. So frustrating, especially since we took care of the fuel starvation issues with all of your help. Anyone got some new thoughts?

 

[Snoop]

Hello from Germany,
I had the same problems with my M151 A2!
Engine lost power above 40mph.
I removed the small metal-fuelfilter in front of the carb. and cleaned it with compressed air.
After that the MUTT droves like new.
Meanwhile I replaced the old fuelfilter.

Bye
Snoop