1991 140 Looper. starting, compression, fuel flow

Ran fine for the past few months, on the river the other day was towing someone in whose motor died, engine sputtered and died.. started messing with it today, if I pump the bulb up and start it it will run for a bit and then die out.. if I pump it again before dying it will keep going for a bit.. anywhere between 15 seconds to a minute or so..

I popped off the fuel pump line running to the distribution tree, turned it over and it shoot fuel..

I tried blowing back in the inlet line to see if maybe was an air leak somewhere and it was closed, so I assume the lines are good at least to the bulb..

Bought new plugs a bit ago, so went ahead and put them in, give a few tries nothing.. I take the plugs out they look to be covered in oil, not so much gas but more so oil...

I hooked a compression tester up and got readings of 35, 35, 37, 38...
Am I reading this wrong.. is it possible for the motor to even run at that low of compression?

And what is my next step? I pulled the carbs and was planning on disassemble/clean tomorrow and giving that a try before dropping the 150 on rebuild kits...

I am the most confused at the compression readings, I used a tester once a long time ago.. screw it in, turn the motor a good few times until the needle maxes out right? Motor was cold at the time, hadn't been running in an hour or so if that has a bearing...

The only other thing I can think that might have any effect is that the spark advance got moved earlier in the day of the original issue, however I am fairly sure I got it reseated back to where it previously was.

Thanks in advance

Re: 1991 140 Looper. starting, compression, fuel flow

Time for a new compression guage. Had the same problem 2 yrs ago, my mechanics guage indicated 35psi, he said it would cost $xxxx to rebuild.
I said screw it and bought my own guage, now I have 85psi.

Sounds like fuel pump is worn if you can keep it going with the bulb.
The only way to test the pump is with a guage designed for it.
But your troubleshooting points at the pump.

Don't bother doing the carbs until you get the kits, its a waste of time.
Do them one at a time incase you lose track and be carefull not to mix up the high and low speed jets.

Re: 1991 140 Looper. starting, compression, fuel flow

Agree, check compression with a different gauge for comparison. Did fuel shoot consistently with gushing spurts for at least 10 seconds ???

Re: 1991 140 Looper. starting, compression, fuel flow

You should be reading 120 PSI or better if all the plugs are out and the starter/battery is good. I would recommend that you try a different gauge.

It's not at all likely but possible that you could blow both cylinder head gaskets while towing.

Re: 1991 140 Looper. starting, compression, fuel flow

kenmyfam said:

Did fuel shoot consistently with gushing spurts for at least 10 seconds ???

Click to expand...

I turned the motor over for maybe 3 or 4 seconds, it wasn't a constant flow but spurts, and they were definitely 'gushing', hit a friend in the arm that was standing on the other side of my driveway.

ezeke said:

You should be reading 120 PSI or better if all the plugs are out and the starter/battery is good.

Click to expand...

I didn't even notice this until the third time I read it... I didn't have all the plugs out, just replaced one at a time with the gauge... will go recheck in the proper manner shortly..

Re: 1991 140 Looper. starting, compression, fuel flow

Just to be safe, I returned the Autozone loan-a-tool compression tester and went and picked up a new one.

Pulled all the plugs and the readings I got are below.. cold motor and turned it over for 10-15 seconds each time until the needle stopped rising..

Recommendations on where to go from here?

Re: 1991 140 Looper. starting, compression, fuel flow

I assume that cylinder #4 is similar to the 3 photos you posted.
That is mighty low compression !!!
Pop a little oil down the plug holes and see what difference it makes.

Re: 1991 140 Looper. starting, compression, fuel flow

I got the 4th pic posted up now..

Just some 2cyl oil? There is some dark liquid on the tester every time I pull it out so I know theres at least a mixture of gas/oil in it at the moment..

Re: 1991 140 Looper. starting, compression, fuel flow

Oil is not likely to bring those readings back in line. I believe that you should pick up two cylinder head gaskets and take a look at the cylinders.

Re: 1991 140 Looper. starting, compression, fuel flow

ezeke said:

take a look at the cylinders.

Click to expand...

I thought the same, as far as I can tell the walls are scored slightly but smooth, the gasket seems intact all be it quite dirty. Examples attached.

Part 1 of 2 for attachment limits.

Re: 1991 140 Looper. starting, compression, fuel flow

Part 2 of 2.

Re: 1991 140 Looper. starting, compression, fuel flow

ezeke said:

Oil is not likely to bring those readings back in line. I believe that you should pick up two cylinder head gaskets and take a look at the cylinders.

Click to expand...

Agree. Oil is a quick comparison without removing anything.

Re: 1991 140 Looper. starting, compression, fuel flow

What were the compression readings with the new gaskets?

Re: 1991 140 Looper. starting, compression, fuel flow

ezeke said:

What were the compression readings with the new gaskets?

Click to expand...

I have not obtained them yet, I was going to head to the local marina tomorrow and attempt to.

Re: 1991 140 Looper. starting, compression, fuel flow

Stopped by the local repair shop to check about gaskets..
Mother-in-laws friend is one of the mechanics there, offered to come to the house and check the situation for me..

Brought his compression gauge, all reading between 130-140...

Apparently the gauge I originally loan-a-tool'd from Autozone AND the one I bought there were leaking/damaged/broken... we even double checked the one I had after getting his readings and it reported the same faulty numbers. Bad luck I guess...

He's checking to see if he has a fuel pump in his yard that we can switch out and go from there.. his feeling is that it is the fuel pump..

Will give an update once I get another installed, be it one he has or a 350$ replacement...

I appreciate greatly the guidance I have gotten so far from you guys.