PCM GT40 Fuel Pumps Not Priming, Searched Already
Printed From: CorrectCraftFan.com
Category: Repairs and Maintenance
Forum Name: Engine Repair
Forum Discription: Engine problems and solutions
URL: http://www.CorrectCraftFan.com/forum/forum_posts.asp?TID=38475
Printed Date: October-07-2024 at 12:24pm
Topic: PCM GT40 Fuel Pumps Not Priming, Searched Already
Posted By: BWalt302
Subject: PCM GT40 Fuel Pumps Not Priming, Searched Already
Date Posted: April-22-2016 at 12:05pm
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I have replaced both the Fuel Pump Relay and the other one beside it (not sure what that is for) I have checked to make sure no circuit breakers are tripped. There are no blown fuses. Boat does not have a lanyard. All connections seem clean and tight. Battery is brand new and kept charged. I have spark, the rotor button on the dist. seems okay. The fuel pumps (high and low are both running based on feel) ONLY come on when I jump the STO connector. They will run automatically when I jump the red and green wires on the relay (ECO Circuit?) What does this indicate and where should I look in order to get it to prime when turning the key without jumping or grounding anything? I have fuel going to the rail, and the boat will start if I run the pumps via the jumper method, so I think everything is good in the system, I just need to find out why they won't prime with the key like they are supposed to. I have read about checking pin 52 at the ECM and something about pins 40 and 60 but am not the best with a multi meter, can someone give me a detailed explanation on how to test those, do I check with the computer plugged in or just from the harness plug? Thanks for any help! The boat DOES NOT have an FCC. It is the 1996 PCM Pro Boss GT-40 EFI engine. |
Replies:
Posted By: sport1999
Date Posted: April-22-2016 at 1:06pm
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While you wait for others to respond, here is a good read for fuel and circuit issues. http://www.correctcraftfan.com/forum/forum_posts.asp?TID=25775&PN=1&title=99-sn-gt40-fuel-supply" rel="nofollow - http://www.correctcraftfan.com/forum/forum_posts.asp?TID=25775&PN=1&title=99-sn-gt40-fuel-supply Lewy2001 is a great resource for the GT-40 engine. Give a good look at his posts in particular. All the way down on the first page from Lewy2001: "Yes the pumps should prime every time you turn on the ignition switch. The ignition switch activates the EEC relay that supplies power to the computer which in turn activates the short prime cycle for fuel pumps. The EEC relay also supplies the power to activate the fuel relay. So it could be either relay or connections." Also mentioned in the thread, grab the GT-40 Troubleshooting guide from the site if you haven't already. Not sure how different it is for your pre-FCC engine. |
Posted By: BWalt302
Date Posted: April-22-2016 at 9:52pm
| So, I stuck the negative cable on my volt meter into plug 52(blue w/ orange stripe) and the other end on 28 of the fuel pump relay (I think? It was the one that was yellow with a green stripe.). I set the meter to read the lowest OHM setting and when I tested the connection with the key on and off it read 1 - when I hit the two ends of the multimeter together, it reads 0.1 or 0 - so does this mean my pin 52 is not grounding? If so, where do I check to further diagnose? |
Posted By: lewy2001
Date Posted: April-24-2016 at 10:02am
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Brandon measure the resistance between pin 52 & ground. It should go from open circuit (very high resistance) to short circuit (very low resistance zero ohms) when you first turn the ignition on. ------------- If you're going through hell, keep going http://www.correctcraftfan.com/diaries/details.asp?ID=2999" rel="nofollow - 89 Ski <a href="http://www.correctcraftfan.com/diaries/details.asp?ID=5685" ta |
Posted By: BWalt302
Date Posted: April-24-2016 at 6:14pm
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Thanks! So positive pin stuck in 52, other to ground. I get nothing, just an infinite resistance. |
Posted By: lewy2001
Date Posted: April-24-2016 at 9:24pm
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That is correct infinite resistance (open circuit) it should go close to zero ohms when the key is turned on for a few seconds. If this does not happen the ECM is not functioning correctly. I would check all the earth points from the ECM to the engine. The main earth (-ve) from battery bolts to bell housing and there is another earth point on the back of observer side cylinder head. Make sure you have ground (earth/negative) at pins 40 and 60 of the ECM. Clean up all the ground points and meter (ohm test) them back to the main earth point on engine, should be close to zero. If you touch the meter leads together on smallest ohm range that is the reading you should see when it is short (close zero ohms). I think you mentioned that the engine runs fine if you jumper the STO to earth and make the pumps run all the time. You could lake test it to make sure the ECM provides every other signal required for the engine to function correctly (ignition and injectors). ------------- If you're going through hell, keep going http://www.correctcraftfan.com/diaries/details.asp?ID=2999" rel="nofollow - 89 Ski <a href="http://www.correctcraftfan.com/diaries/details.asp?ID=5685" ta |
Posted By: BWalt302
Date Posted: April-24-2016 at 11:00pm
| Well, it tries to run if i jump the pumps, more like it hits and sometimes fires up for at most 3 seconds sputtering out. So it wouldnt run to lake test it i was checking pins with the ecm unplugged. I guess i should leave that plugged in for other tests? |
Posted By: BWalt302
Date Posted: April-25-2016 at 12:50am
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So with the computer plugged in, 40 and 60 ( I think are the two black ones on the right side, top and middle, they were labeled) both of those wires have a short circuit (0.2 on my meter) 52 with the computer plugged in, turning the key remains in an infinite resistance, so nothing changes when I turn the key on... I did notice that when I turn the key off it jumps to a high resistance for a second and goes back to infinite. |
Posted By: BWalt302
Date Posted: April-25-2016 at 12:56am
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So Im guessing its a bad computer... Can I use a regular 351W ford computer? I think I remember reading that there was only a difference in tunes from PCM and may run with less performance. |
Posted By: lewy2001
Date Posted: April-25-2016 at 1:11am
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No you cannot use a regular Ford EEC1V computer it needs to have the correct PCM firmware program. It is all pointing to a bad ECM.  They are still available could not find them on Nautique Parts but give them a ring and check if they can get one. Skidim list the http://www.skidim.com/MODULE-58L-GT40-MPI-EEC/productinfo/R116009/" rel="nofollow - GT40 ECM ------------- If you're going through hell, keep going http://www.correctcraftfan.com/diaries/details.asp?ID=2999" rel="nofollow - 89 Ski <a href="http://www.correctcraftfan.com/diaries/details.asp?ID=5685" ta |
Posted By: BWalt302
Date Posted: April-25-2016 at 1:23am
| Ahh, well I pulled mine apart and found a broken resistor (R262) I am going to try soldering a new one in and see if that fixes it. If not, I guess I will be buying a new ecu :( |
Posted By: BWalt302
Date Posted: April-25-2016 at 1:39am
| Is there a difference in ECMs for EFI vs Carb engines? Natique parts has them but needs an engine serial number to get pricing and availablility, wonder why. |
Posted By: lewy2001
Date Posted: April-25-2016 at 9:47am
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No the Gt40 ECM is only for that engine only. There was a later revision of the ECM but they should be all interchangable. ------------- If you're going through hell, keep going http://www.correctcraftfan.com/diaries/details.asp?ID=2999" rel="nofollow - 89 Ski <a href="http://www.correctcraftfan.com/diaries/details.asp?ID=5685" ta |