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Need some GT40 help gents

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firehorse5_0 View Drop Down
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    Posted: July-29-2017 at 11:59am
Here is the story, first two times out with my '96 SPN she ran like a top. Third time I got into a bay with some weeds and overheated the engine a bit. Now it will not accelerate. Here is a list of things I have checked.

Exhaust is clear
Fuel pressure is 35-40 psi at idle and under load
Compression 120 psi on all 8
Timing is 5* BTDC and advances with throttle
Plugs look fine
Spark is strong

I am at a loss, it seems to have everything it needs. Any ideas would be appreciated.
Also there is a DLC next to the ECM but when I plug my Diagnostic tool in to it it shows a message " must connect to DLC" ? Will a Diagnostic tool not work with these ECM?

Thanks
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Post Options Post Options   Thanks (0) Thanks(0)   Quote tryathlete Quote  Post ReplyReply Direct Link To This Post Posted: July-29-2017 at 12:14pm
Overheated a bit.... more detail please. Exhaust clear-- are you 100% positive the rubber exhaust hose didn't collapse inside as it is designed to do when overheated? I'm suspicious.
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Post Options Post Options   Thanks (0) Thanks(0)   Quote tryathlete Quote  Post ReplyReply Direct Link To This Post Posted: July-29-2017 at 12:22pm
Is the impeller still functioning? If it ran dry due to water intake or strainer being clogged, not sure if power would wind up being restricted via engine safe-mode.
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Post Options Post Options   Thanks (0) Thanks(0)   Quote firehorse5_0 Quote  Post ReplyReply Direct Link To This Post Posted: July-29-2017 at 12:29pm
The light caught my attention around 220, shut down as the needle continued to climb probably hit 240. It did damage the rubber connection at the manifold which I have replaced . I removed the tubes and muffler and inspected them as well as the rest of the couplings.
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Post Options Post Options   Thanks (0) Thanks(0)   Quote firehorse5_0 Quote  Post ReplyReply Direct Link To This Post Posted: July-29-2017 at 12:32pm
Yes, engine runs at 160* no problems.
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Post Options Post Options   Thanks (0) Thanks(0)   Quote tryathlete Quote  Post ReplyReply Direct Link To This Post Posted: July-29-2017 at 1:08pm
Originally posted by lewy2001 lewy2001 wrote:

That is the "SLOW" limp mode on the GT40 engine. The GT40 uses extra switches (not senders) to sense low oil pressure and high engine temp. The computer then limits rpms.

Easy to trouble shoot just remove wiring from both switches.

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Post Options Post Options   Thanks (0) Thanks(0)   Quote tryathlete Quote  Post ReplyReply Direct Link To This Post Posted: July-29-2017 at 1:10pm
Who knows if the high temp may have damaged the temp sensor--worth a try to remove the wire from the sensor to see if your problem goes away.
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firehorse5_0 View Drop Down
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Post Options Post Options   Thanks (0) Thanks(0)   Quote firehorse5_0 Quote  Post ReplyReply Direct Link To This Post Posted: July-29-2017 at 4:01pm
Thank you for that info it is definitely something to check. Wouldn't the warning light stay on though?
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Post Options Post Options   Thanks (0) Thanks(0)   Quote firehorse5_0 Quote  Post ReplyReply Direct Link To This Post Posted: July-31-2017 at 2:17am
Took a look at the impeller today it was in pretty bad shape. Got it replaced and took the boat too the lake for a trial still no good. I was working on checking the temp sensors and ran out of daylight. Did get a double check on some things. Fuel pressure is great 35 PSI goes to 40 under load. Starts fine, idles good, it will rev in nutral, but put it under load and she is not happy . Well I have four days to think about it before I can work on it again. I sure would like to get my scan tool to communicate with the ECM.
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Post Options Post Options   Thanks (0) Thanks(0)   Quote fgroce Quote  Post ReplyReply Direct Link To This Post Posted: July-31-2017 at 8:39pm
Any Ford EEC-IV scan tool will work.
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Post Options Post Options   Thanks (0) Thanks(0)   Quote firehorse5_0 Quote  Post ReplyReply Direct Link To This Post Posted: August-09-2017 at 4:01pm
I took the sport to the lake for more testing last weekend and tried removing the tan/black wire from the temp and oil pressure senders to no avail. I also rechecked timing, checked plug wires, looked for any damaged wiring, all looked good. I checked the MAP sensor as well it is in range key on no vacuum 150hz-103hz @ 20 in. I had my fuel pressure gauge installed the whole time and every time I advanced the throttle it went to 40 PSI and stayed there I know the regulator closes to allow more volume of fuel flow but it it seems like maybe my injectors are not delivering enough fuel which is exactly what it feels like. So the injectors are second on the list to check after the ignition module which is about the last thing I can think of. I will be working on it again this weekend so any other ideas or input is welcomed.

Thanks
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Post Options Post Options   Thanks (0) Thanks(0)   Quote Bri892001 Quote  Post ReplyReply Direct Link To This Post Posted: August-09-2017 at 6:28pm
This is a long shot, but if this was a carbed boat, your symptoms sound a bit like a vacuum leak. Could rev in neutral but won't stay running in gear.

Maybe check to make sure no gaskets were damaged around the throttle body/intake manifold etc.
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Post Options Post Options   Thanks (0) Thanks(0)   Quote Dreaming Quote  Post ReplyReply Direct Link To This Post Posted: August-09-2017 at 8:01pm
I am not a GT-40 owner, but your initial timing sounds low to me.   Most guys here are running 10° BTDC.    I would check initial against a book number, and then check final to be between 32° and 34°, but those are the numbers for a carbed boat, they may be different for an injected boat.
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Post Options Post Options   Thanks (0) Thanks(0)   Quote fgroce Quote  Post ReplyReply Direct Link To This Post Posted: August-09-2017 at 9:26pm
Make sure you pull the spout connector up by the distributor. This disables the computer advance so you can set it. Set it to what the book says, I think it is 5 BTDC, but double check. I looked it up in the GT 40 manual.
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Post Options Post Options   Thanks (0) Thanks(0)   Quote KENO Quote  Post ReplyReply Direct Link To This Post Posted: August-09-2017 at 11:24pm
You say "it won't accelerate" that's not very descriptive,

Kinda hard for anybody to help with that description of the problem

Not that an overheat should affect your timing, but a couple people are giving you timing numbers of 10 degrees, I'd probably read the manual and find out that it says 5 degrees before TDC with the spout connector removed like fgroce said, then plug it back in when you're done setting it to 5.and it will be more advanced than it was when you set it with the computer now controlling the timing

Is that how you checked it or is it at 5 with the connector hooked up ?

Is it safe to assume you've read the manual especially the troubleshooting section ?

Lots of pages in it..
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Post Options Post Options   Thanks (0) Thanks(0)   Quote firehorse5_0 Quote  Post ReplyReply Direct Link To This Post Posted: August-10-2017 at 12:18am
Thanks for the input guys!
@ Dreaming , as a Ford guy my gut would tell me 10° base as well but, the engine cover has a placard listing 5° BTDC base timing for the GT40.

@ fgroce I know about the spout but thanks for the reminder.

@ KENO. It starts fine, idles fine maybe just a hint of something wrong, hit the throttle and it says grrrr and goes forward but feels like 100 HP instead 300HP.

I agree an overheat should not effect timing but, whenever I have a problem I start with the basics.

I don't have a manual for the boat. I am going off of my fairly good knowledge of EEC-IV Fords and research on this site.

Thanks again for your time gents.
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Post Options Post Options   Thanks (0) Thanks(0)   Quote MourningWood Quote  Post ReplyReply Direct Link To This Post Posted: August-10-2017 at 1:07am
If you're saying that the boat was running great, then it clogged and quickly overheated, and now runs poorly, I can't see how the timing would have changed. Nor the spark plugs.
I appreciate the 'start from basics' approach, however, usually if you have an "incident", and the boat ran perfectly previously, now runs differently, it can be traced to the "incident".
Check the diode between "water temp switch" and ECA....
....or is there more...?
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Post Options Post Options   Thanks (0) Thanks(0)   Quote lewy2001 Quote  Post ReplyReply Direct Link To This Post Posted: August-10-2017 at 2:35am
That does not sound like a limp(SLOW) problem. Does it rev normally when stationary?

The old petrol (gas even though it is a liquid) in a spray bottle squirted into the intake can help in diagnosing if it is a fuel injector problem.
If you're going through hell, keep going

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Post Options Post Options   Thanks (0) Thanks(0)   Quote KENO Quote  Post ReplyReply Direct Link To This Post Posted: August-10-2017 at 8:13am
Firehorse

You really do have a GT 40 manual, you just don't know it (till now anyways )

Go to the reference section here on CCF and you'll find it, all 301 pages .

Or click on this link
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Post Options Post Options   Thanks (0) Thanks(0)   Quote firehorse5_0 Quote  Post ReplyReply Direct Link To This Post Posted: August-10-2017 at 3:50pm
That manual is very helpful! I didn't realize it was on here. It has values for all the sensors so I can test them properly now. I really think that is where my problem lies. Logic would dictate that because this condition was caused by an overheat it either melted a wire or fried a sensor. I have looked over the wiring twice now and it is fine so....

I have had separate issues happen at the same time in the past hence my start with the basics approach.

A far as the timing goes I just stated base timing for the record. I was really just checking to make sure that it was advancing since the advance is computer controlled.
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Post Options Post Options   Thanks (0) Thanks(0)   Quote firehorse5_0 Quote  Post ReplyReply Direct Link To This Post Posted: August-12-2017 at 2:18pm
It was the plugs.. Found it by touching the exhaust right next to the head immediately after starting the engine. Had three cylinders not getting hot. Spark was good at the wire so I switched the plug to another cylinder and the problem followed it. A trip to NAPA and $20 later and she is running like a top.

Thanks for the advice you all helped me get it diagnosed.
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Post Options Post Options   Thanks (0) Thanks(0)   Quote Bri892001 Quote  Post ReplyReply Direct Link To This Post Posted: August-16-2017 at 1:14pm
Nice, glad you found it

Seems like an odd coincidence, but I guess stuff like that happens. Wonder if it did go into SLOW mode, usually the default mode of fuel injected engines will run richer... so maybe this fouled the plugs? Who knows, but if it's fixed, it's fixed. That great. I'll document this in the GT-40 thread.
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