| Author |
Message |
    
Nigel Dineen
New member
Username: budleigh1
Post Number: 1
Registered: 09-2009
| | Posted on Tuesday, September 29, 2009 - 05:07 pm: | 
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Hi, Whilst browsing the net I have just come across this website and I must say there seems to be some very knowledgeable and helpful contributors.
I just wondered if someone could perhaps advise me on what could be the cause of the problem with my boat. It's a 1990 Four Winns 255 Sundowner fitted with the OMC Ford 7.5 Liter motor.
The problem is it will start and run just fine across the entire rev range, you can take the boat for a run with no problems at all for anything up to about half an hour, then all of a sudden and without warning the motor dies and will not re-start for about 3 hours until it has cooled right down.
At the time of the motor dying I have checked and there is no spark at the plugs. Once the motor has cooled there is a spark once again and the motor starts with no problem. This fault is regular in that it always occurs after approx 30 mins of running.
I have had a marine mechanic look at it and he has carried out some replacement of the wiring loom where corroded and bad connections have been found and rectified, the spark plugs, wires, kill switch and the neutral safety switch have all been replaced but this is starting to cost me some serious money and I think the mechanic is now just guessing at what could be wrong, he now thinks it's the crankshaft sensor which could be failing once it's warmed up.
As I am based in England we don't have as many knowledgable people on OMC's so can anyone help please. |
Bob Hill
Senior Member
Username: boatin_bob
Post Number: 1441
Registered: 07-2006
| | Posted on Tuesday, September 29, 2009 - 09:28 pm: |
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Unfortunately you have one of those dreaded Spitfire ignitions, could be the unit itself that is getting hot and quits working. There are inputs to it like the timing sensor and the knock sensor, even though the low oil and high temp switches. One idea would be to take a can of freon (spray coolant) and when it fails try spraying the case to see if cooling it down will get it working quicker, at least this will help narrow down the failing unit. These units are next to impossible to find, some guys have even converted over to a regular distributor.
This link will show you a wiring diagram for that engine.
http://www.selocmarine.com/content/manuals/3404/pdf/340410w160.pdf |
chiefalen
Advanced Member
Username: chiefalen
Post Number: 272
Registered: 03-2008
| | Posted on Wednesday, September 30, 2009 - 06:29 am: |
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here is a site that my friend bought a dist. from all one unit coil and dist.. one wire in one wire out.
You can call them for a ford unit, and if you look at the website they have ford ones also. Whole thing should be under 100 bucks delivered. |
Bob Hill
Senior Member
Username: boatin_bob
Post Number: 1442
Registered: 07-2006
| | Posted on Wednesday, September 30, 2009 - 09:38 am: |
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Hey Chief...nice site! Where is it???  |
Nigel Dineen
New member
Username: budleigh1
Post Number: 2
Registered: 09-2009
| | Posted on Wednesday, September 30, 2009 - 05:00 pm: |
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Bob, I have just looked at the wiring diagram you sent and things make a bit more sense now, I think the oil pressure switch is for an audible alarm and the oil sender is for the pressure guage. As for the temp switch this must also be for an audible alarm and the sender must be for the temp guage.
I don't think any of these would cut the engine, please tell me if I am wrong. |
Bob Hill
Senior Member
Username: boatin_bob
Post Number: 1443
Registered: 07-2006
| | Posted on Wednesday, September 30, 2009 - 07:34 pm: |
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Nigel..yes the oil/temp senders feed the gauges, the oil/temp switches feed the EEM (Spitfire) this system has a built in feature called SLOW( Speed Limiting Operational Warning), this will activate by either the oil/temp switch, causing the engine to only reach a max RPM of 2800 until the problem is fixed, however that's for a correctly operating one, not sure if one that goes flaky could be causing your problem? |
chiefalen
Advanced Member
Username: chiefalen
Post Number: 273
Registered: 03-2008
| | Posted on Wednesday, September 30, 2009 - 09:01 pm: |
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http://cgi.ebay.com/ebaymotors/SMALL-BLOCK-BIG-CHEVY-HEI-Distributor-SBC-BBC-GM- 65-000_W0QQcmdZViewItemQQ_trksidZp4634Q2ec0Q2em14Q2el1262QQhashZitem4ceacc0d10QQ itemZ330356755728QQptZMotorsQ5fCarQ5fTruckQ5fPartsQ5fAccessories
can't believe i didn't post the site, see what happens when you get older then g-d. |
Nigel Dineen
New member
Username: budleigh1
Post Number: 3
Registered: 09-2009
| | Posted on Monday, October 12, 2009 - 02:46 pm: |
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Hi, I have just been down to the boat today and ran it until it stopped. First I sprayed the crank sensor with pipe freezing coolant, no joy. Next I liberally sprayed the spitfire ignition unit and guess what, she started straight away. I can now assume its a problem with the main ignition unit and will get in touch with the company selling the distributors on the link from chiefalen.
Thanks for all your help so far, I will let you know how I get on with getting a distributor.
Regards,
Nigel. |
chiefalen
Advanced Member
Username: chiefalen
Post Number: 287
Registered: 03-2008
| | Posted on Monday, October 12, 2009 - 04:12 pm: |
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once again sorry about the first non post of the site.
They say the first thing to go is the memory i can't remember if i forgot something. or is it i can't remember if i care to remember. |
Nigel Dineen
Member
Username: budleigh1
Post Number: 4
Registered: 09-2009
| | Posted on Monday, October 12, 2009 - 05:21 pm: |
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Well, I'm glad you did remember eventually. I have just been looking at that website and their distributors look very reasonably priced. I shall be calling them in the next day or so to see if they can supply one that's suitable.
Thanks again. |
