FishHunt23
Seaman
- Joined
- Jan 4, 2007
- Messages
- 50
I've got a 1988 Evinrude 70 VRO that I'm having some problems with. I would sure appreciate any advice!
Motor has a history ... it was partially submerged and recently rebuilt (professionally), including a new crankshaft and water pump. VRO/Oil was disabled so I'm mixing gas. I completed the break-in (during which these same problems occurred), am now running 50:1 gas and have installed new plugs.
Problems I'm having:
1) Does idle well. I have adjusted idle speed, but it doesn't help. I need to keep the idle speed quite high to keep it running. Same thing when motor is in gear ... if I don't keep the RPM's high enough it will stall. Depressing the key to activate the primer does help keep it running in both instances. Sometimes when I am in gear the motor won't rev up to the appropriate RPMs for the throtttle position, and depressing the key/activating the primer will goose it to get me up to speed. Once I'm out of idle range RPMs it runs fine, until...
2) Motor cuts out after it is warm. If I make a run of several miles the motor will start cutting out intermittently. By "cutting out" I mean that I'll be running along at mid to high RPMs (say 5500, which is a guess as I don't have a tach) and very suddenly the motor will drop to a low rpm (fast idle speed, guessing 2500) and then just as quickly jump back up to full speed. This problem occurs only after running the engine for a while, so I presume that it is related somehow to its temperature (i.e. only happens when motor is warm). The problem starts out with a cut-out every so often - maybe every 30 seconds - and increases in frequency until it is happening every couple of seconds. Eventually, after a few minutes of increasing cut-outs, the motor will bog down to the point that I can only run it at the lower RPMs (2500 in my example here) no matter how far down the throttle is. When I push the throttle down past say 1/2 position, it bogs worse. When I ease up on the throttle, it bogs less but still doesn't run right. Once I get to this point (where the motor won't run above 2500 RPMs) it will run rougher and rougher, and start stalling, and eventually I won't be able to get it started again. I'll get it home, and the next time I take it out it will run just fine (with the exception of the poor idle) until the same problem occurrs in just the same fashion (after the engine runs for a while).
I spoke to a mechanic friend of mine and he thought a faulty ignition coil was to blame. His thought was that that the bad coil was failing once it got warm and that I was running on 2 of my 3 cylinders when that happened (explaining the 5500 to 2500 RPM jumps). When the bad coil finally stops working all-together it leaves me with 2 cylinders. Eventually, those two cylinders are flooding out which explains the stalling and eventual inability to re-start the engine.
To find the bad coil I would have to run the engine until this problem occurs, and the have a friend crank the engine while I locate the plus that isn't firing. But that assumes that the plug won't fire when I'm grounding it ... which is might do. In that situation I would have a really tough time finding the bad coil. Is there an easier way? New coils aren't expensive and look really easy to install, so I'm thinking of just replacing all three. Is there an easier way??? Alternative theories?
Obviously, the ignition coil theory makes sense to me ... but the poor/rough idle concerns me as well. Could it be that i have a bad fuel pump as well? Or could the bad ignition coil also be causing the rough idle, even though it only seems to be failing after runninig a while?
My current thought is that I should replace the faulty coil if I can locate it, or all three if I can't. Hopefully that fixes everything. I assume it will fix the "cut-out" problem. If not, I'm out $60 and back to the drawing board. If my idle problems persists after replacing the coils, I'll replace my gas line (which does appear to be working fune but is older). If that doesn't help the idle, I think I'll need to consider rebuilding or replacing the fuel pump.
Thanks for reading my very lengthy description. Any thoughts or comments at all will be very much appreciated.
Motor has a history ... it was partially submerged and recently rebuilt (professionally), including a new crankshaft and water pump. VRO/Oil was disabled so I'm mixing gas. I completed the break-in (during which these same problems occurred), am now running 50:1 gas and have installed new plugs.
Problems I'm having:
1) Does idle well. I have adjusted idle speed, but it doesn't help. I need to keep the idle speed quite high to keep it running. Same thing when motor is in gear ... if I don't keep the RPM's high enough it will stall. Depressing the key to activate the primer does help keep it running in both instances. Sometimes when I am in gear the motor won't rev up to the appropriate RPMs for the throtttle position, and depressing the key/activating the primer will goose it to get me up to speed. Once I'm out of idle range RPMs it runs fine, until...
2) Motor cuts out after it is warm. If I make a run of several miles the motor will start cutting out intermittently. By "cutting out" I mean that I'll be running along at mid to high RPMs (say 5500, which is a guess as I don't have a tach) and very suddenly the motor will drop to a low rpm (fast idle speed, guessing 2500) and then just as quickly jump back up to full speed. This problem occurs only after running the engine for a while, so I presume that it is related somehow to its temperature (i.e. only happens when motor is warm). The problem starts out with a cut-out every so often - maybe every 30 seconds - and increases in frequency until it is happening every couple of seconds. Eventually, after a few minutes of increasing cut-outs, the motor will bog down to the point that I can only run it at the lower RPMs (2500 in my example here) no matter how far down the throttle is. When I push the throttle down past say 1/2 position, it bogs worse. When I ease up on the throttle, it bogs less but still doesn't run right. Once I get to this point (where the motor won't run above 2500 RPMs) it will run rougher and rougher, and start stalling, and eventually I won't be able to get it started again. I'll get it home, and the next time I take it out it will run just fine (with the exception of the poor idle) until the same problem occurrs in just the same fashion (after the engine runs for a while).
I spoke to a mechanic friend of mine and he thought a faulty ignition coil was to blame. His thought was that that the bad coil was failing once it got warm and that I was running on 2 of my 3 cylinders when that happened (explaining the 5500 to 2500 RPM jumps). When the bad coil finally stops working all-together it leaves me with 2 cylinders. Eventually, those two cylinders are flooding out which explains the stalling and eventual inability to re-start the engine.
To find the bad coil I would have to run the engine until this problem occurs, and the have a friend crank the engine while I locate the plus that isn't firing. But that assumes that the plug won't fire when I'm grounding it ... which is might do. In that situation I would have a really tough time finding the bad coil. Is there an easier way? New coils aren't expensive and look really easy to install, so I'm thinking of just replacing all three. Is there an easier way??? Alternative theories?
Obviously, the ignition coil theory makes sense to me ... but the poor/rough idle concerns me as well. Could it be that i have a bad fuel pump as well? Or could the bad ignition coil also be causing the rough idle, even though it only seems to be failing after runninig a while?
My current thought is that I should replace the faulty coil if I can locate it, or all three if I can't. Hopefully that fixes everything. I assume it will fix the "cut-out" problem. If not, I'm out $60 and back to the drawing board. If my idle problems persists after replacing the coils, I'll replace my gas line (which does appear to be working fune but is older). If that doesn't help the idle, I think I'll need to consider rebuilding or replacing the fuel pump.
Thanks for reading my very lengthy description. Any thoughts or comments at all will be very much appreciated.
