why can't I find a fuel pump relay on my '79 308 gts??
Because it doesn't have one -- the current draw for a small carb fuel pump like on a 308 is only a few amps so it just passes directly thru the ignition switch. Why are you looking for one -- are you having fuel pump trouble?
long story....owned my car over 15 years without any problems! Drove home few months ago and turned off the ignition but car kept on running (REALLY running....like I never turned it off) Due to MANY other car projects, I've basically let the car sit for a few months but now I had some time to get into it. I initially thought it was the ignition switch itself so I dropped the steering column and pulled the switch out and checked it out. It seemed fine so I reassembled the everything and looked elsewhere. Whenever I connect the battery (no key in ignition), the fuel pump goes on. If I remove fuse #3 it goes off. I have a wiring diagram that shows a fuel pump relay so I figured maybe it was stuck "on", but its obviously not one of the relays on the main board because I removed each one and the fuel pump kept running. I figured maybe the relay was mounted in some remote location. Now what?
Well, that is an unusual problem, and I can't see how it could be caused by anything but a bad ignition switch or maybe a non-stock wiring modifiaction (the wiring diagram you have must not be for a '79 carbed 308 -- if your 308 is a US version, the one you need is the one in the back of the 150/78 North American OM). Do you have any non-stock wiring modification connected to the top of fuses #1, #2, or #3? The way it is supposed to work is +12V from the battery (a large, R, red wire) is connected to terminal 30 of the ignition switch; the large "A" (light blue) wire connected to the top of fuse #2 comes from the ignition switch terminal 15 and should only be +12V when the key is "on". The bus bar strip on the back of the fuseblock connects the tops of fuses #1, #2, and #3 together -- so when the light blue wire goes +12V when the key is "on", the top of all three fuses #1, #2, and #3 go to +12V. My advice would be to remove the large light blue wire from the top of fuse #2 and measure the voltage relative to ground when the key is "off" (and the battery is connected) -- if it is always +12V then something is wrong with the ignition switch or its wiring, so the next thing to do would be to remove the light blue wire from the terminal 15 tab on the ignition switch and then measure the voltage from the terminal 15 tab on the ignition switch to ground -- if this is +12V with the key "off" then the ignition switch must be bad. Good Hunting!
Pull left fuses A, and B leaving the fuel pump relay in place which is an easy way to check for improper voltage with the ignition off. A, B, and C fuses are bused together at the top of the fuseblock. If voltage is there, recognized by fuel pump operation with fuses A and B removed, and ignition off, the voltage can only be coming from the headlight stalk or alternator which re the other things wired to that point which could provide fuel pump voltage. If there isn't voltage, recognized by fuel pump operation with fuses A replaced but fuse B removed and ignition off, the voltage must be coming from somthing connected to fuse A. Repeat with A out and B replaced. ditto You do need a proper wiring diagram. http://www.ferrariwiring.com/ I should acknowlege credit to Steve for similar reasoning. But instead of getting out a voltmeter to check for voltage and pulling wires off, first pull fuses and use the sound of the fuel pump...quicker and it's there.
My electrical skills are not as good as those above but I've seen a few ignition switches go bad. I might try ignition switch on and off a few times and jiggle at the same time to see if that makes the fuel pump go off. Mostly high mileage vehicles though and most often when people put a large weight on the key like 50 keys and lots of key rings. Not so likely on a 308 given the space constraints around there. Good luck.
Many thanks to Steve et all---here's where I'm at. My ignition switch is absolutely NOT the problem (confirmed with many tests). The problem is that the first 3 fuses are being powered with key OFF by the yellow/black striped wire on the bottom of fuse #1. When connected and battery connected, voltmeter reads 12 v to fuses 1,2, and 3. When disconnected, these fuses no longer powered unless ignition key switched to "on" and car starts normally. Seems fuse #1 goes to windshield wiper so now I need to find short?? vinnie
I was looking at this today with Vinnie. Let me try to narrow down what we found. First of all the steering column is disconnected and all of the connectors are disconnected. The ignition switch checks out OK. We connected the battery. If we go to the left fuse block positions 1 , 2 and 3 (jumpered together at input side) we get +12V on the downstream of position #1 with ignition switch off. This backfeeds the fuses of 2 and 3 (fuel pump). We removed the downstream wire on fuse #1 (2 wires both yellow with black tracer). One of these wires goes into a relay and we haven't traced it down yet. We need to do more work here but for now Vinnie is going to reassmle the steering column and ignition switch. After that we wll need to find out what these 2 yel/blk wires go to. Somehow there is +12V feeding into one or both of these wires. With these wires disconnected the ignition switch works as it should. This is a 1979 GTS carb. car , so if someone with a good wiring diagram for a 79 could see where these 2 wires go we would appreciate it. All of the wiring is in excellant shape so we find it hard to believe there is a worn/stripped wire but it may be possible. Also the OEM fuse block is solid with no loose rivits or burn marks. Once again this was one of those problems that happened during a drive where when he turned off the ignition the engine (FP) would not shut off. We can get the car to run now without these wires connected but still need to find the problem. Thanks
Is this a US version '79 308 GTS? What's odd is that the US '78-'79 schematic (in the 150/78 OM) only shows 1 GN (yellow/black) wire connected to the bottom of fuse #1 (that goes to run the hazrad switch). And this GN wire is shown as being partnered with a R (red) wire that goes to run the brake light switch -- and neither the GN nor R wire "goes into a relay". If you can confirm US or euro version, I'd be glad to post a section of corresponding fuseblock schematic showing the wires connected to fuses # 1, 2, and 3 for you to compare with what's on the car.
Steve-- US version best I know......I bought it (in 1995) from major Ferrari dealer. Anyhow, interesting also that the "blue wire" is on top of fuse #3, not #2 as you suggested. Hmmm...
No functional problem with where the three wires going to the top of fuses #1, 2, and 3 are located (since they are all connected together by the fuseblock busbar anyway), and you're not the first to report having some shifting around (but best to match the schematic IMO). Here's the US fuseblock from the 150/78 OM schematic: Image Unavailable, Please Login Still puzzled by your report of the presence of a 2nd GN wire at the bottom of fuse #1 -- is the associated relay where it connects something someone added or is it one of the "stock" relays?
You mentioned the yellow/black at fuse 1, it goes to the Hazard switch. Ya gotta admit it's so much easier to troubleshoot with a decent wiring diagram. _________________________ http://www.FerrariWiring.com Image Unavailable, Please Login
Paul , great. We'll need to see if the problem lies in the HW switch/circuit or if it is the Fan relays. The other blue wire is OK and does not have +12v when switch is off. So it looks like one of the 2 yellow wires we are after. Thanks , we'll keep plugging away and let you folks know what we find. I assume that the 78-79 are the same. For my own information do you have your upgraded schematic for a 77 GTB? Thanks again.
Yes, my package contains both 1977 and 1978 308 cars. The primary difference being cat circuitry. I excised the drawing above from the 1978 diagram. _______________________________ http://www.FerrariDiagrams.com
Steve the funny thing is and I'm trying to recall from yesterday there are only 3 wires on the downstream of fuse #1. On one connector are 2 yel/blk wires and on the other connector is the blue wire. I did not recall seeing the red wire but need to take another look. Considering we just got 6" of snow this morning I won't be looking at the car for a few days. As to one of these yellow wires going into a relay it looks like it goes into the back of the relay panel . We'll need to get more into it. We were happy we found part of the problem and eliminated the ign. switch as a potential problem. After Vinnie gets the column back together we'll keep the yel/blk wire off and see what doesn't work. Thanks for the help here.
I'm in no rush The yellow wire going into the relay panel (and to a relay) is for the windows -- you can see this yellow wire in Paul's partial diagram -- so no question there. In your original post you said: "...We removed the downstream wire on fuse #1 (2 wires both yellow with black tracer). One of these wires goes into a relay and we haven't traced it down yet...." conveying that the wire's color going to the relay was yellow/black. If it's yellow = no mystery; if it's yellow/black = mystery. Absolutely good progress! Keep us posted.
I know that it's still the holiday season -- so maybe not your highest priority, but any new information/diagnosis yet Steve/Vincent? Since I can't recall anyone ever reporting this particular symptom before, it has, naturally, aroused my technical curiosity .
Steve I don't want to steal Vinnie's thunder but he and a couple of gearheads found the problem last night. It was the Hazard Warning Switch. It appears that fuse #6 is +12v all of the time and the downstream wire goes to the antenna switch and the Hazard warning switch. So even though I did not see the switch Vinnie emailed me today and said it was broken. I assume the insides were screwed up and the +12v backfed up to fuse #1 which is buss barred to fuse #3 which is the fuel pump fuse. That's why the engine wouldn't shut down with the key off. That's my guess so problem solved. They took the switch out of the loop and all works correctly. The next question is there a replacement HW switch at a reasonable (I know , don't say it) price that can be purchased.
Thanks for the update on your findings. Don't know of the best priced source for a replacement, but it does seem a somewhat confusing issue (euro different than US? 4 or 7 terminals?) based on my brief look -- and a lot of price variation from ~$60 to ~$450.
