hhdinyuma Posted April 9, 2007 Share Posted April 9, 2007 Car still won't start after double impact at CS last month. Here's what I know so far. No fuel pressure. Fuel pump, lines and filter all are intact. When master power is on and starter is engaged, 0 VDC at the pump. Hot wire the pump with 12 VDC and pump spins and works fine. Car starts and runs fine. How wire 16 AMP fuse in drivers compartment with 12 VDC. Car starts and runs fine. Replaced fuel pump relay with a new one from Paragon, no effect. Any thoughts? DME? Impact/G switch? Please help! Quote Link to comment Share on other sites More sharing options...
Big Dog Posted April 10, 2007 Share Posted April 10, 2007 Could it be the DME inside the fuse box. If you have another one, you might try it. There is also a way to jumper across two of the dme sockets to power the fuel pump. If that works, the dme might have gotten jolted. I can send you a fax showing the sockets on the dme plug and mark which two to use a jumper wire on if you need it. Jim Foxx Quote Link to comment Share on other sites More sharing options...
944-Spec#94 Posted April 10, 2007 Share Posted April 10, 2007 Jim, Fuse box is different on your 88 as compared to Hal's 83. However the DME/Fuel pump relay can still fail. It is rather common problem on all street 944's. However the fix is easy as the ports can be jumpered (same jumper for all cars so your jumper diagram should work) for testing and the relays are cheap. Hal first go after the relay. Quote Link to comment Share on other sites More sharing options...
hhdinyuma Posted April 10, 2007 Author Share Posted April 10, 2007 Jim, Thanks. I would like a copy of the diagram. You can FAX it to 928-329-9754. No cover sheet necessary. BTW, hows the recovery coming? I have already replaced the fuel pump relay on the main fuse panel with a new one. Is that the DME/Fuel Pump Relay you are talking about Joe? It was my first thought after I determined the fuel pump was working properly when the DME/Relay was bypassed. Replacing the relay did not fix the problem. Q: Does the fuel pump relay only receive power after the starter is engaged? I have assumed this since the fuel pump normally isn't running with just the ignition on prior to engine start, (I think). Quote Link to comment Share on other sites More sharing options...
944-Spec#94 Posted April 10, 2007 Share Posted April 10, 2007 Yes this is the relay I am talking about. Fuel pump gets power when the key is "on" in the "run" position. the starter engagement only causes the starter to crank over. So no power to the fuel pump is an problem. Probably relay, but you may also want to trace the wiring in the back of the car. Something may have cause the wires to not be connected anymore. BTW.... if you apply 12v to the relay it should audibly "click" over and if you rig up some wires you can test the relay as well. If the wires to pump are good and the relay is good you may want to check in on a DME unit. The impact may have caused something to fail inside the DME. I have spare 83 DME I can send you if needed. Quote Link to comment Share on other sites More sharing options...
hhdinyuma Posted April 10, 2007 Author Share Posted April 10, 2007 Joe, I think I DO need the DME. I have applied 12VDC to the Fuel Pump Fuse on the secondary fuse panel in the drivers compartment. When voltage is applied here, the fuel pump runs and the car starts and runs fine. This leads me to the conclusion that the wiring to the pump downstream of the fuel pump relay is good. SInce replacng the fuel pump relay with a new one had no effect on the problem, I have pretty much concluded the only thing left is the DME. Do you agree? My DME is an early style mounted under the steering column. Is that what you have. If so, how could I get it from you? Thanks, Quote Link to comment Share on other sites More sharing options...
944-Spec#94 Posted April 10, 2007 Share Posted April 10, 2007 SInce replacng the fuel pump relay with a new one had no effect on the problem, I have pretty much concluded the only thing left is the DME. Do you agree? My DME is an early style mounted under the steering column. Is that what you have. If so, how could I get it from you? Thanks, Ok, that makes sense. I have an 83 parts car so I'd just need to pull the DME from the car and send it. DME works, but it would be a good idea to check to be sure there is a stock chip in there. This is easy on the early DME's since it would need to have clearly visible stocked chip. When do you need it? I can send it via mail. Quote Link to comment Share on other sites More sharing options...
hhdinyuma Posted April 10, 2007 Author Share Posted April 10, 2007 Joe, Thanks a bunch. I am trying to get the car ready for PIR May 5/6 so the sooner you can send it the better. I need to get it running so I can get it on the trailer for a trip to the body shop to pull out the damage on the rear. I will PM you with my address. Let me know what I owe you (besides my undying gratitude!) Is is possible or even advisable to use the chip out of my existing DME in case the one in yours is not stock? Thanks, Quote Link to comment Share on other sites More sharing options...
944-Spec#94 Posted April 10, 2007 Share Posted April 10, 2007 Joe, Thanks a bunch. I am trying to get the car ready for PIR May 5/6 so the sooner you can send it the better. I need to get it running so I can get it on the trailer for a trip to the body shop to pull out the damage on the rear. I will PM you with my address. Let me know what I owe you (besides my undying gratitude!) Is is possible or even advisable to use the chip out of my existing DME in case the one in yours is not stock? Thanks, Ok, I see if I can get in the mail Wedensday. Quote Link to comment Share on other sites More sharing options...
bcc1323 Posted April 11, 2007 Share Posted April 11, 2007 fyi: I bypassed the relay and put the dme and the fuel pump on sep. switches. So far it has worked well.. Quote Link to comment Share on other sites More sharing options...
944-Spec#94 Posted April 11, 2007 Share Posted April 11, 2007 Hal, I have the DME ready to send today but... You said you have no power to the fuel pump when the starter is engaged? Does the starter turn over or is there no power at all? Is there power to the fuel pump with key in the "run" position? Many years ago my ignition switch failed and the car would die in the run postion, but work fine during starts. Bypassed the ignition switch with my own and it worked fine. Maybe it is not the DME after all. So let me ask a few more questions 1. Fuel pump works when power is applied? - Correct? 2. If you apply external 12 VDC to the pump does the engine start and run? 3. If you jumper the DME/Fuel Pump relay can you get power to the fuel pump? 4. With the key in the "run" position do you have power to the DME RELAY. IE is there power going through the circuit and then power at pump if jumpered? 5. Do you lose power at the fuel pump when turning the key to the "start" position. Like I said I will still have my wife ship the DME as it is already packed today, but I am starting to think it may not be a DME issue. Feel free to try it out once you get it however. Quote Link to comment Share on other sites More sharing options...
hhdinyuma Posted April 11, 2007 Author Share Posted April 11, 2007 Joe, I can't explain exactly why, but I just now got it running. I pulled out everything, both fuse panels, dme, etc. When I did I finally got continuity across the fuse block between the fuel pump relay and the fuel pump fuse. Don't know for sure if it was causing the problem, but I did find a melted connection on the fan relay (the one next to the fuel pump relay). I removed the fan relay, which was bypassed already, and the circuit including the fuel pump relay worked. Only thing I can figure is maybe the shorted/malfunctioning fan relay had shut down the dme preventing fuel pump activation. Either that or removing everything reseated a connection somewhere??? Anyhow, thanks for all the help. All I really know at this point is that the car starts, don't know how it runs at speed yet. If your wife already mailed the dme, I will bring it with me on the 5th of May and reimburse the mail cost. Thanks again, Quote Link to comment Share on other sites More sharing options...
944-Spec#94 Posted April 11, 2007 Share Posted April 11, 2007 Well, She mailed it this morning. You can give it back to me next event. Unfortunalty I will be out of town for the May 5/6 event. You should bring it anyway as maybe you give it to one of the other local Phoenix guys and it can get back to me that way. It is a spare so I don't need it ASAP or anything. BTW... feel free to swap it when you get it if you still run into issues. Quote Link to comment Share on other sites More sharing options...
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