stall at idle and not enough fire

[dunk68]

I recently bought a boat with a 1972 Evinrude. I had it serviced and the first guy messed it up sorta bad, had the carbs rebuilt and the timer base was in the wrong position. I had it fixed by another person and It ran fine in the yard on the muffs, but the first time on the water it barely idles and stalls. It would idle for just a minute or two, wouldn't take throttle and it sounded like it was barely running. WHen I got it back home it fired fine one time, but sounded like the motor was missing, and then I had the same problem I had in the lake. Now all it will do is Idle for just a minute but it's barely running and you can hear the piston (blow air?, puff or something) when it stops. The tech said it is losing fire. Any ideas?

 

[jtexas]

Re: stall at idle and not enough fire

welcome to the forum.

We'll need a little more information...such as...what horsepower? model number would be helpful.
Also compression and spark test results.

 

[dunk68]

Re: stall at idle and not enough fire

it's a 100 hp, 100293R electric shift. The compression was 120 give or take on all cylinders. I'm not sure on the spark test.

 

[jtexas]

Re: stall at idle and not enough fire

Good compression.

Let's rule out some easy fuel problems: Is the fuel line holding pressure? Fuel tank vented? Fresh fuel? Does pumping the primer bulb while it's running smooth it out any?

Do this cylinder drop test:
Determine which cylinder(s) aren't hitting by pulling the spark plug wires one at a time with the engine idling. If the RPM's don't decrease noticeably, that cylinder's dropped out. Use a spark-plug-wire-puller (couple bucks at auto-parts store), or a person you don't like very much, to avoid getting shocked. Or insulated pliers, something like that.

And a spark test:
Get a spark plug tester (couple bucks at auto-parts store), set the gap for 7/16" and test each plug wire, look for strong blue spark.

Also pull the plugs after she's been idling, make a note of what they look like and if any are different from others, which hole they came from. They should be slightly oily (not clean and shiny, not dry), insulator should be tan to golden brown, nothing broken, little bit of carbon deposit on the rim is normal, no silver flecks. They should be Champions. If they're more than a couple years old, or you don't know how old they are, wouldn't hurt to replace 'em.

When it dies, does it restart easily?

Did the first guy, the one who screwed it up, do anything else?

Did your tech link & sync when he did the carbs and timer base, and tank test the motor? Reason I ask is, If you get good spark, then it's just about got to be fuel and/or timing. Which you probably already paid for.

Let us know what ya get.

 

[dunk68]

Re: stall at idle and not enough fire

Good compression.

Let's rule out some easy fuel problems: Is the fuel line holding pressure? Fuel tank vented? Fresh fuel? Does pumping the primer bulb while it's running smooth it out any?

Do this cylinder drop test:
Determine which cylinder(s) aren't hitting by pulling the spark plug wires one at a time with the engine idling. If the RPM's don't decrease noticeably, that cylinder's dropped out. Use a spark-plug-wire-puller (couple bucks at auto-parts store), or a person you don't like very much, to avoid getting shocked. Or insulated pliers, something like that.

And a spark test:
Get a spark plug tester (couple bucks at auto-parts store), set the gap for 7/16" and test each plug wire, look for strong blue spark.

Also pull the plugs after she's been idling, make a note of what they look like and if any are different from others, which hole they came from. They should be slightly oily (not clean and shiny, not dry), insulator should be tan to golden brown, nothing broken, little bit of carbon deposit on the rim is normal, no silver flecks. They should be Champions. If they're more than a couple years old, or you don't know how old they are, wouldn't hurt to replace 'em.

When it dies, does it restart easily?

Did the first guy, the one who screwed it up, do anything else?

Did your tech link & sync when he did the carbs and timer base, and tank test the motor? Reason I ask is, If you get good spark, then it's just about got to be fuel and/or timing. Which you probably already paid for.

Let us know what ya get.

 

[dunk68]

Re: stall at idle and not enough fire

Thanks for all the tips to try. I'll try it as soon as I can. The plugs are new Champions, New Fuel tank, line, fresh fuel, vented tank. Primer bulb doesn't help, but it did seem to start easier with the choke left open after cranking. It will restart quite easily, but it barely runs for less than a minute. The plugs are slightly oily on all 4 cylinders.
The first guy replaced the flywheel, I was there when it sheared the pin and the old flywheel was scarred in the keyway. He replaced the coils and stator assembly with used parts and put the timer base on the wrong way. He also rebuilt the carbs and fuel pump.

The 2nd guy is a friend that owns the Mercury repair shop. One of the carbs was set to wide open at idle and was pouring gas out of the bottom of it. So he adjusted the timer base and tightened and adjusted the carbs. I recently bought this boat and motor and haven't bought a repair manual for this motor yet. I'll order one today. I know little about boat motors, but it looks like I'm going to learn. Everyone I talk to says buy another motor, it's an electric shift, nobody wants to work on it.

The only Evinrude shop is 70 bucks an hour 50 miles away.

Good compression.

Let's rule out some easy fuel problems: Is the fuel line holding pressure? Fuel tank vented? Fresh fuel? Does pumping the primer bulb while it's running smooth it out any?

Do this cylinder drop test:
Determine which cylinder(s) aren't hitting by pulling the spark plug wires one at a time with the engine idling. If the RPM's don't decrease noticeably, that cylinder's dropped out. Use a spark-plug-wire-puller (couple bucks at auto-parts store), or a person you don't like very much, to avoid getting shocked. Or insulated pliers, something like that.

And a spark test:
Get a spark plug tester (couple bucks at auto-parts store), set the gap for 7/16" and test each plug wire, look for strong blue spark.

Also pull the plugs after she's been idling, make a note of what they look like and if any are different from others, which hole they came from. They should be slightly oily (not clean and shiny, not dry), insulator should be tan to golden brown, nothing broken, little bit of carbon deposit on the rim is normal, no silver flecks. They should be Champions. If they're more than a couple years old, or you don't know how old they are, wouldn't hurt to replace 'em.

When it dies, does it restart easily?

Did the first guy, the one who screwed it up, do anything else?

Did your tech link & sync when he did the carbs and timer base, and tank test the motor? Reason I ask is, If you get good spark, then it's just about got to be fuel and/or timing. Which you probably already paid for.

Let us know what ya get.

 

[dsinger]

Re: stall at idle and not enough fire

If it has a clipper switch remove it.

 

[guywithboat]

Re: stall at idle and not enough fire

Get a spark tester and make sure you hava a nice thick spark, usually 3/8 in. If the coil needs to be replaced, you can use an universal automotive coil, works great.