1970 Evinrude 25HP Ran ok, then quit afer 30 minutes and restart but stall

[ncpi]

Just picked up the engine on a boat I purchased, so I don't really know the history. This is a 250002E model. While knowledgeable about engines, both 2 and 4 stroke, I haven't much experience with outboards.

Test drove it last weekend on the fuel left in the tank, ran ok. Probably put 20-30 minutes on it

Took it out today. Fresh fuel (93 octane, no ethanol) with Pennzoil 2 Stroke Outboard oil TC-W3 mixed 50:1. It ran ok for the first 30 minutes or so, then suddenly lost power and quit. It would restart, but then quit right away. Let it cool about 20 minutes. Same thing. It would help if I would choke it, but still would not stay running for more than a 10 seconds or so. Has good compression based on the pull starter "feel"

Seems like maybe a fuel pump problem to me. Anything common with these engines that might cause this? Any way to test the fuel pump? Suggestions greatly appreciated.

 

[Daviet]

Re: 1970 Evinrude 25HP Ran ok, then quit afer 30 minutes and restart but stall

If the engine will run properly if you contine to squeeze the primer bulb, you have a fuel pump problem or an air leak in the fuel line from the tank to the pump. You can remove the fuel line from the pump to the carb and pull the engine over, if you get fuel pulsing out of the hose your pump is working properly.
Are you using a plastic tank, is the vent open?

 

[lindy46]

Re: 1970 Evinrude 25HP Ran ok, then quit afer 30 minutes and restart but stall

Also make sure it's pumping water and cooling ok.

 

[ncpi]

Re: 1970 Evinrude 25HP Ran ok, then quit afer 30 minutes and restart but stall

If the engine will run properly if you contine to squeeze the primer bulb, you have a fuel pump problem or an air leak in the fuel line from the tank to the pump. You can remove the fuel line from the pump to the carb and pull the engine over, if you get fuel pulsing out of the hose your pump is working properly.
Are you using a plastic tank, is the vent open?

Thanks I'll the fuel pump test today. Good reminder on the vent in the plastic tank cap. I didn't even think about it (duh), but when I checked this morning it was open.

Lindy46. good question on the cooling. Overheating was one of my worries. I think it probably wasn't overheating as it wouldn't run very long (just seconds) after I let it cool down for a good 20 minutes and it still had good compression and would fire. I am a rookie with this engine though, how can I tell if its pumping adequate water? And the really dumb question, where is the water pump located...didn't seem obvious to me.

 

[pdaly28]

Re: 1970 Evinrude 25HP Ran ok, then quit afer 30 minutes and restart but stall

Thanks I'll the fuel pump test today. Good reminder on the vent in the plastic tank cap. I didn't even think about it (duh), but when I checked this morning it was open.

Lindy46. good question on the cooling. Overheating was one of my worries. I think it probably wasn't overheating as it wouldn't run very long (just seconds) after I let it cool down for a good 20 minutes and it still had good compression and would fire. I am a rookie with this engine though, how can I tell if its pumping adequate water? And the really dumb question, where is the water pump located...didn't seem obvious to me.

I agree with lindy46.Sound like its getting hot.can you hould your finger on the cyl.head very long when it's running.is it flowing water from the tell tale.Did you replace the impeller?

 

[AlTn]

Re: 1970 Evinrude 25HP Ran ok, then quit afer 30 minutes and restart but stall

marineengine.com has diagrams of your engine....look under the gearcase group and you'll find the water pump impeller, housing, etc....

 

[ncpi]

Re: 1970 Evinrude 25HP Ran ok, then quit afer 30 minutes and restart but stall

I disconnected the carb line from the fuel pump. Made sure when I gave it a prime from the fuel bulb that fuel shot out. Good stream there. Pulled the plugs and turned it over, didn't seem to be more than a good drip (not a strong "shot") on each pulse coming out of the fuel pump. How much fuel should squirt out of the pump each time? Does this sound like enough?

I have not had it running since leaving the lake yesterday, so I can't tell how hot it gets to the touch when running. The Muffs I bought for hose cooling are round and they don't fit well so I need to go back this week to the boating store and get the rectangular ones instead. I did not replace the impeller, maybe I need to. I'll go look in the gearcase section, thanks for the pointer to marineengine.

Thanks for all the help so far

 

[AlTn]

Re: 1970 Evinrude 25HP Ran ok, then quit afer 30 minutes and restart but stall

modern muffs probably won't work on your motor...test it in a barrel with water ~ 4" or so below the exhaust relief holes < nostrils > on the rear of the exhaust housing

 

[ncpi]

Re: 1970 Evinrude 25HP Ran ok, then quit afer 30 minutes and restart but stall

Any input on just how much fuel should spurt out of the fuel pump on each pulse when I turn the engine over?

 

[Daviet]

Re: 1970 Evinrude 25HP Ran ok, then quit afer 30 minutes and restart but stall

You should get a good squirt every time the fuel pump pulses.

 

[ncpi]

Re: 1970 Evinrude 25HP Ran ok, then quit afer 30 minutes and restart but stall

I think its rather weak then, I wouldn't call it a "good squirt", more like a big drip. Looks like I have to replace the whole pump, not just the diaphrams unless I am reading the parts online incorrectly. Is there just a rebuild kit for the fuel pump?

A couple other questions.

While I am ordering parts, think I will get a new water pump impeller as well. Are there any gaskets or seals that need to be replaced when you open it up to replace the impeller? None seem obvious from the pictures.

Last... The plugs in the engine were Champion J6C. One was a little bit oily (and black), the other was dry, but still black. Seems the correct plug is a J4C (gapped at 0.030) per the marineengine web site, however thats a cooler plug isn't it? With the current one's black, My first reaction is not to go with a "cooler" plug to the J4C. However, I'd appreciate the experienced folks weighing in...think I should replace with J4Cs or J6Cs?

 

[lindy46]

Re: 1970 Evinrude 25HP Ran ok, then quit afer 30 minutes and restart but stall

If the water pump housing and base plate are fairly clean and smooth, just replace the impeller - nothing else needs to be replaced. Make sure the pin is in place and not worn down too much, as the pin is the only thing that drives the impeller. If you do a lot of trolling, I'd use the J6C plugs, as they have less tendency to foul out.

 

[ncpi]

Re: 1970 Evinrude 25HP Ran ok, then quit afer 30 minutes and restart but stall

Thanks! I'll get the parts on order and report back here on my experience. Probably be a couple weeks.

One thing I noticed is the fuel pump on mine didn't have the gasket (part #14 on the link below) between the pump and the engine. Also the part number in raised numbers on my existing fuel pump housing was 312631. Wonder if someone had replaced it with the wrong one (they sure didn't put the gasket in there).

http://www.marineengine.com/parts/j...manufacturer=Evinrude&section=Powerhead+Group

 

[lindy46]

Re: 1970 Evinrude 25HP Ran ok, then quit afer 30 minutes and restart but stall

That could be causing your problems without a good seal there.

 

[ncpi]

Re: 1970 Evinrude 25HP Ran ok, then quit afer 30 minutes and restart but stall

That could be causing your problems without a good seal there.

I agree. I thought about just getting the gasket but went ahead and ordered the fuel pump too. Thanks too for the hint on the pin for the impeller, for $1.74 I ordered one of those in case I need it. Hate to get the thing apart only to find out I have to make another order and wait for a pin. Found J6C plugs at the local O'Reilly Auto parts for $1.99 each

 

[ncpi]

Re: 1970 Evinrude 25HP Ran ok, then quit afer 30 minutes and restart but stall

Here's my update after finally getting to work on the outboard.

First, just want to clear this up in case others read this. The part number on the fuel pump housing (312631) must have been just that sub-part part number as he new replacement pump had the same number on it - its not the overall fuel pump assembly part number.

I installed the new fuel pump (and the gasket that wasn't there before) and test ran the engine in a big bin of water. Engine ran well, but I noticed there was no water coming out the water exhaust port. Let it run until the cylinder felt pretty hot, no water.

After the engine cooled down for a couple hours, I pulled the thermostat as I figured that would be easier than dropping the lower unit. Didn't seem to be any evidence of water in the cavity. The thermostat wasn't stuck, I could move it, but it was open just the smallest amount when cool. Put the plate back on without the thermostat and ran the engine again. Still didn't see water coming out. Time to pull the lower unit.

After pulling the lower unit and looking at the impeller, I really didn't think it looked too bad. I ran water down the inlet and outlet for the thermostat section and made sure water ran out the ports and things weren't clogged. Since I had a new impeller and pin, went ahead and replaced them. I turned the drive shaft clockwise as I put the water pump cover on (per the manual). I re-installed the lower unit and test ran again (w/o the thermostat). Viola....water coming out the water exhaust! Success!

Took the thermostat, put it in an old pan with water and put it on the stove. It did not open further even when the water boiled (Temp is supposed to be 145 degrees).

My conclusion. I think the engine may have overheated originally and it may not have been the fuel pump/missing gasket although it certainly needed the gasket. I do think the thermostat is bad but I rally am not sure why it didn't pump with the original impeller. While the vanes were "formed" in a curved shape I would have thought it would have still pumped, but I guess not. The new impeller definitely made the driveshaft very hard to turn manually after it was installed. It was not like that with the old impeller.

For now I will leave the thermostat out until I get a replacement and a new gasket. Its easy to access and replace when I do get one. I also have to get to the lake again and test it on a long term run to be sure all is well, but I think I have fixed all the possible causes.

Thanks for everyone's help.

...Bill

 

[ncpi]

Re: 1970 Evinrude 25HP Ran ok, then quit afer 30 minutes and restart but stall

Finally got it to the lake today. Ran perfectly all day!

 

[AlTn]

Re: 1970 Evinrude 25HP Ran ok, then quit afer 30 minutes and restart but stall

good to hear..thanks for posting back with results