Lehr propane utboard bogs down

[ERTF]

I have a 5hp Lehr propane outboard that came with my trawler. I starts right up. And runs fine thru the rpm range, but then after awhile it tends to bog down at full throttle to the point I might as well just throttle back to about 2/3rds because thats all i'm getting. Also have had issues with it getting bad enough that it would die.

Any opinions on the cause?

 

[HopCar]

If you are using the 1 pound bottles of propane they can get cold enough to reduce the amount of propane gas that comes out as they get below half full. It causes exactly what you describe.

Try running it on a large barbeque tank connected by a hose and see if the problem goes away.

There is a Lehr owners group on Facebook that you can download service and parts manuals from.

 

[HopCar]

If the problem isn’t a cold bottle, the next thing to look at is the fuel vaporizer. It uses engine cooling water to warm liquid propane and turn it into vapor the engine can run on. Maybe the water flow is blocked and it’s freezing up. I’m just pulling that off the top of my head. I’ve never actually seen it. Get the service manual and see what it has to say.

 

[ERTF]

I'm using a 10lb fiberglass tank, but it's down to about 1/6th full if that makes any difference.

 

[ERTF]

If the problem isn’t a cold bottle, the next thing to look at is the fuel vaporizer. It uses engine cooling water to warm liquid propane and turn it into vapor the engine can run on. Maybe the water flow is blocked and it’s freezing up. I’m just pulling that off the top of my head. I’ve never actually seen it. Get the service manual and see what it has to say.

This might be it because I noticed the telltale was just a smattering spray when i was testing it yesterday.

 

[HopCar]

I'm using a 10lb fiberglass tank, but it's down to about 1/6th full if that makes any difference.

Yes, as the tanks get low there is less surface area to warm the liquid propane and boil it to vapor. Refill the tank and see if the problem goes away.

 

[SteveK]

I hope a full 10lb tank will solve your problem. I bought a 5HP mercury propane only because of the problem you describe with Lehr. Sounds like the regulator.

Sorry to bring you the bad news, it is the reason they went out of business. There was a slew of bad parts out of China and they stopped honoring warranty.

 

[HopCar]

You say you don’t have trouble starting it. When you disconnect the hose from the tank air will get in the system and you’ll need to bleed it next time you want to start it. Do you know how to do that?

 

[ERTF]

You say you don’t have trouble starting it. When you disconnect the hose from the tank air will get in the system and you’ll need to bleed it next time you want to start it. Do you know how to do that?

No I had no idea that was necessary. I also was hearing/smelling intermittent propane leaks from the first couple fittings in the engine, but it seems like i got those to stop.

 

[ERTF]

I hope a full 10lb tank will solve your problem. I bought a 5HP mercury propane only because of the problem you describe with Lehr. Sounds like the regulator.

Sorry to bring you the bad news, it is the reason they went out of business. There was a slew of bad parts out of China and they stopped honoring warranty.

Why did you buy another propane outboard? Doesn't make any sense for regular use. Fuel is too hard to get and typically more expensive.

I've had this thing sitting here for 3 years. The pvc roll up it was matched to was dead on arrival. I've have a 14ft cc skiff with a 60hp. I only still have this lehr because i've always figured I couldn't get much for it. Finally trying to decide if it's worth keeping as a backup -- which would require me to drop $700 on a pvc rollup -- or if I should just cut my losses...

 

[HopCar]

If you ever have trouble starting it you need a short piece of wire to bleed it. With the propane hooked up remove the engine cover. You’ll see a small hole in the center of the regulator. Gently push the wire, a paper clip works well, into the hole and listen for hissing. This is the air being pushed out by propane. Let it hiss for maybe five or ten seconds. It should start right up after that.

 

[KnotYet]

Why did you buy another propane outboard? Doesn't make any sense for regular use. Fuel is too hard to get and typically more expensive.
(edit)...

Propane has 27% less energy per given volume so if gasoline is going for $5.00
per gallon then propane should be more than $3.65 according to your statement.

Yesterday I paid $3.37 per gallon for propane. So it is currently 10% cheaper here.

I'm not aware of anyplace where propane is particularly hard to find, either.

 

[HopCar]

Soo Valley brings up some interesting points. Lehr is out of business and parts are very hard to find. When something major breaks on yours I suggest you just replace it. Until then use it and enjoy it.

You mentioned hearing leaks. Lehr had problems with a batch of their internal fuel hoses. The fittings were not crimped tight enough to the hose. I don’t know any way to fix this except replace the hose assembly.

The reason I bought two Lehr engines is because they can sit long periods of time and start right up. No gasoline to clog the carburetor.

I think that a propane outboard is a great idea for small engines. I worked several boat shows with Bernardo the founder of Lehr. He had a vision of making larger and larger propane engines and I think he tried to push it too fast. I think they would still be in business if he had stopped making bigger engines and concentrated on quality control and improvements for the smaller engines. He also needed to make the five and nine hp engines with a 25” shaft and high thrust prop and gear box for sailboat auxiliaries. They also needed to add a priming button on the outside so you could bleed the system without removing the cover. It’s too bad, I really like propane as a small engine fuel.

 

[SteveK]

I wanted propane instead of gas for several reasons IF they stood up to my intense research. Lehr was everywhere at supposed discounts (BS), they were being dumped. It was easy enough to find bad reviews and customers with new anchors when parts were not available.

Then Mercury commissioned Tohatsu, a well respected manufacturer, and the rest is history, I did not hesitate. Propane is available on every corner around here and I use it for the stove/oven and BBQ on board.

ERTF. This is my first propane outboard, not second. I have no complaints after two seasons of use. But it does not use 1lb propane bottles, so I use a 10lb

 

[SteveK]

BTW, the early built Lehr made in America are probably still in use. The downfall was when they found a cheaper source for parts from China. We all know how the Japanese can make a better widget.

 

[HopCar]

Soo Valley, you’re not missing anything not being able to use the 1 pound canisters. At six horsepower you’d get only about half an hour run time.

 

[ERTF]

Propane has 27% less energy per given volume so if gasoline is going for $5.00
per gallon then propane should be more than $3.65 according to your statement.

Yesterday I paid $3.37 per gallon for propane. So it is currently 10% cheaper here.

I'm not aware of anyplace where propane is particularly hard to find, either.

Well that's why I said typically. Right now is a bit of an anomaly with gas prices spiking due to ukraine, while domestic propane not very much affected.

Even so, I bought rec90 yesterday for $4.30, but I'm sure that price will be up next time i re-up my jugs.