| Author |
Message |
    
Marc Sylvester
Member
Username: marctreese
Post Number: 20
Registered: 05-2009
| | Posted on Tuesday, June 30, 2009 - 08:52 pm: | 
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Replaced my bad distributor this afternoon, forgot to mark the rotor placement and engine runs fine at idle but when reaching 3000rpms it backfires from the carb.
tried moving the distributor back and forth left and right slightly and further and still the same result.
any thoughts? this is on a volvo aq131b. |
El Pescador
Senior Member
Username: el_pescador
Post Number: 4575
Registered: 02-2006
| | Posted on Tuesday, June 30, 2009 - 09:09 pm: |
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Do you have two ignition wires swapped by any chance? The firing order is 1-3-4-2. |
Marc Sylvester
Member
Username: marctreese
Post Number: 21
Registered: 05-2009
| | Posted on Tuesday, June 30, 2009 - 09:59 pm: |
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I'll have to double check that tomorrow. I'm pretty sure its 1-3-4-2. I just filled the tank with 3/4 of a tank of high test fuel and re timed the engine when installing the distributor.
When its idling (about 1000RPMS) or running below 3000, this thing purrs... hopefully I can figure this out.
IF the firing order is correct, what do you think I should check next while I'm out there tomorrow afternoon? |
El Pescador
Senior Member
Username: el_pescador
Post Number: 4576
Registered: 02-2006
| | Posted on Tuesday, June 30, 2009 - 11:03 pm: |
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Check that the accelerator pump is working, and also that the timing advances from 6º-10ºBTDC at idle to about 32º-36ºBTDC at 4200RPM. In any case, the timing should be fairly advanced by the time you reach 3000 RPM. If not, maybe your new distributor has some problems (broken springs/seized centrifugal weights). |
Marc Sylvester
Member
Username: marctreese
Post Number: 22
Registered: 05-2009
| | Posted on Wednesday, July 01, 2009 - 09:20 am: |
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I'll check the timing and see, hopefully tonight or tomorrow. If the accelerator pump was faulty would the engine just die rather than backfire? Just curious and I know your the expert. I'm by far a mechanic.
thanks for the feedback i will let you know after I check timing. |
El Pescador
Senior Member
Username: el_pescador
Post Number: 4577
Registered: 02-2006
| | Posted on Wednesday, July 01, 2009 - 09:55 am: |
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If the accelerator pump is worn, stuck or for whatever reason is not squirting all the way, the engine will have a lean air to fuel ratio during the acceleration process, and that could cause backfire in the intake manifold. |
Marc Sylvester
Member
Username: marctreese
Post Number: 23
Registered: 05-2009
| | Posted on Thursday, July 02, 2009 - 11:45 am: |
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I did a huge no no i think! another boat owner told me i may be just a tooth off on the distributor and to do the following:
remove plug #1, manually crank the pulley over until the piston was up all the way, insert the plug again, remove the distributor and advance just under 1/4 inch to the left to move 1-2 teeth and set the rotor to point to the #1 wire location. I did that and now cannot get spark.
Any suggestion that i can try myself? I have another marina i could take it to if needed. |
El Pescador
Senior Member
Username: el_pescador
Post Number: 4582
Registered: 02-2006
| | Posted on Thursday, July 02, 2009 - 12:12 pm: |
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You should get spark, unless you forgot to reconnect the wire that goes from the distributor to the points or the lead coming from the coil is not connected to the distributor cap, or one of the coil wires.
If you installed the distributor in the wrong position, no big problem. Remove #1 plug and turn the engine manually with your thumb covering the spark plug hole until you feel compression, then keep turning the engine until the piston is at TDC. Remove the distributor cap and see to which spark plug lead is the rotor pointing, and that should be the lead for #1 cylinder spark plug. If it is way off, you may be able to correct it by either loosening the distributor hold down screw and roving it in the right direction, or by pulling it again and move it the necessary number of teeth. |
Marc Sylvester
Member
Username: marctreese
Post Number: 24
Registered: 05-2009
| | Posted on Thursday, July 02, 2009 - 02:50 pm: |
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Thanks El. I will try checking those later this afternoon.
I wonder if it could be a problem with the plug wire going from the coil to the center of the distributor cap. |
Marc Sylvester
Member
Username: marctreese
Post Number: 25
Registered: 05-2009
| | Posted on Thursday, July 02, 2009 - 03:18 pm: |
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I believe but will double check those. It's almost sounding like its getting an intermittent spark. Grrrr that ought to be fun to troubleshoot. |
Marc Sylvester
Member
Username: marctreese
Post Number: 26
Registered: 05-2009
| | Posted on Monday, July 06, 2009 - 09:22 pm: |
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Back to square one.... replaced the distributor but now not getting a spark, checked connections on the coil, points are gapped, wires are connected properly. Something is definitely off somewhere.
My father in law is bringing a timing light over tomorrow night so hopefully we can ensure the timing if corrected if needed. |
Marc Sylvester
Member
Username: marctreese
Post Number: 27
Registered: 05-2009
| | Posted on Friday, July 10, 2009 - 09:56 am: |
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Got the boat running again, found a new set of points were sparking intermittently. Waiting on my pertronix to arrive today or tomorrow. I will install that and time the engine with a gun and see if that improves. if not, I'll check the accelerator pump if it still bogs down over 3500 RPMS. |
Marc Sylvester
Member
Username: marctreese
Post Number: 28
Registered: 05-2009
| | Posted on Monday, July 13, 2009 - 02:43 pm: |
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Installed the pertronix kit and boy am I happy I did so! Starts right up with no questions what so ever and the install was very easy. Also replaced my napa coil with a Pertronix Flame-thrower for small money.
I still have the backfire at 3000RPMS but will begin to check out the accelerator pump this week. |
El Pescador
Senior Member
Username: el_pescador
Post Number: 4651
Registered: 02-2006
| | Posted on Monday, July 13, 2009 - 02:58 pm: |
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Good to see that you are making headway. 
Please keep us posted of further developments. |
