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Message |
    
Don Kultti
New member
Username: dkultti
Post Number: 1
Registered: 09-2010
| | Posted on Tuesday, September 21, 2010 - 10:57 pm: | 
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I am trying to get a Gray Marine 4-75 to start and having no luck. Am getting spark, good spark I believe. Am sure it is getting fuel. No joy with starting fluid either, Just an occasional puff. This thing ran a couple weeks ago but when it did rUn, after an hour or so it quit and would not restart. When running it would bog down a bit on acceleration and then clear and sound fine. I am thinking an intermittent stuck valve and intend to do a compression check in the next couple days. Pulled carb and split the bowl from the top assembly. Looked good inside. Verified passages clear and all that. Any help out there? |
mike mcintyre
Member
Username: tyeechaser
Post Number: 12
Registered: 08-2010
| | Posted on Wednesday, September 22, 2010 - 01:39 am: |
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Check the strength of the spark. Stick an insulated screwdriver in the spark plug cap and hold it 1/4 inch from the block. Should get a strong arc from block to screw driver. Check the points to make sure they are polished and totally flat. If points are good and set properly and no strong spark suspect the coil. Hope this helps. Mike
ps I've been told to never tear down the carb. They are normally bombproof. |
kim hartshorn
Member
Username: kimhartshorn
Post Number: 9
Registered: 08-2010
| | Posted on Wednesday, September 22, 2010 - 06:58 am: |
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I would also suspect the coil, especially if you haven't replaced it fairly recently. Also, try starting it at night with the lights off, you will be able to see glowing lightning if you are getting any high voltage leakage from a cracked cap or bad wires. |
kim hartshorn
Member
Username: kimhartshorn
Post Number: 10
Registered: 08-2010
| | Posted on Wednesday, September 22, 2010 - 07:53 am: |
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Just my experience, but every problem I have ever had with a boat engine, no matter how many people told me it was gas related, always turned out to be electrical. Including distributor timing btw, double check and make sure your lockdown is tight and the distriubtor hasn't shifted too far out of timing. |
Don Kultti
New member
Username: dkultti
Post Number: 2
Registered: 09-2010
| | Posted on Wednesday, September 22, 2010 - 11:13 am: |
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For all,
Will look into all items mentioned. I did install a new coil. Visual of the points suggests that they are not too bad. The rotor looks OK. The engine is in a 1946 Century. Don't think it has seen salt water use. It is all very clean. Will let you guys know. Thank you all. - Don |
Don Kultti
New member
Username: dkultti
Post Number: 3
Registered: 09-2010
| | Posted on Wednesday, September 29, 2010 - 01:03 am: |
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Well, I figured out the spark issue. The pole on the distributor that the wire from the coil attaches to was out of position and causing a direct short to the distributor housing. Figured this out by measuring voltages and determining why and where the losses were occuring. When I got to the distributor I remove the cap and rolled the engine and could then see the spark where the short was. Fixed that and she started. However, there are other issues.
Could not keep it running for long. Did a compression check and found that cylinder 1 is at 60 PSI, cylinders 2,3,4 are at 115 PSI. A little squirt of oil to the #1 cylinder and no increase so it looks like valves.
Going to pull the engine and rebuild it.
Next question: Can this be back-fitted with an electronic ignition and a 12 volt system? Am thinking I can have the generator turned into an alternator and can fabricate a bracket for the end of the starter to support the shaft to take the additional torque. Not easy, but doable, I believe while retaining the same basic components.
Any input on the above is welcome.
How about the "BEST PLACE" to order engine rebuild parts from. Is there a best place?
Thanks to all. You guys put me on the right track and I do appreciate that |
mike mcintyre
Member
Username: tyeechaser
Post Number: 13
Registered: 08-2010
| | Posted on Wednesday, September 29, 2010 - 01:18 am: |
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http://www.vannessengineering.com/. This guy treated me very well and is clearly an expert on Gray engines. His focus is on doing the next right thing and attention to customer service. Hope this helps. Mike |
Don Kultti
Member
Username: dkultti
Post Number: 4
Registered: 09-2010
| | Posted on Wednesday, September 29, 2010 - 12:46 pm: |
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Thanks Mike. Will give him a call. - Don |
