Fuel Pump Relay?

Gotta love that wiring . . .
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linzy92

Fuel Pump Relay?

Post by linzy92 »

Hello all, My name is Lindsay and I am new to the forum. I am the Proud owner of a 1981 Fiat spider, awesome little car, but it has been giving me some issues these past few days. It would seem that the fuel pump relay is a little screwy (from what I have been able to find, this seems like a pretty common issue). My father is a mechanic and I am learning so we went to work checking everything out. I'll just run through the full events for you guys, so that you can get a full idea of how this came about.

Let me preface this by saying that the car did have issues starting in the past. Previously it had stopped starting and we had replaced the fuel pump and fixed the grounding which solved the problem for about 2.5 months (I suspect that the fuel pump was fine, but that it was just improperly grounded at the time). The car ran great after that (maybe even better than it did before.
Wednesday night I had a soccer game, so I got some gas (I was running on E at that point) and proceeded to drive for about 40 minutes to my house and then to the field. The car was running perfectly up to that point. No issues while driving and it turned off and seemed perfect when I got out of the car. That night (at about 10ish) when my game was done the car absolutely refused to start. It turned and turned but it just didn't want to do it. My father was with me and he started trying to figure it out, unfortunately it was too dark so we couldn't really dig into anything thoroughly. I have AAA so I called and got the car towed back home. The next day me and my father started trying to figure out what was wrong with it. First we checked the fuel filters, because I had been driving the car very near empty we thought that perhaps one of the filters was plugged up. So we purchased a new one and checked on the filters. One of them (The larger one that comes after the fuel pump) was somewhat obstructed, the smaller one was fine (I suspect that the previous owner had that one replaced previously) So we replaced the larger fuel pump. Tried the car, that wasn't the problem (unfortunately). So we continued on down the line of issues. After that we re-replaced the fuel pump (substituting for the one that it had previously) and still nothing. After that we replaced the air flow meter which we did not think was bad but it was worth a shot, still no luck. We checked the coil to make sure that it was sending a spark, coil was in perfect working order. Continuing down the line we thought that perhaps the fuel pump just wasn't getting power for some reason. So we got the trust test light and checked it out. While the key is in the primed position (point right before starting) the fuel pump was receiving power, right after we attempted to start the car the car would start, it would idle for about 2.2 seconds and then the fuel pump would spontaneously lose power. So from that it seems like the fuel pump relay was not functioning properly. Is there anything else that it could be? And is there something that we might be missing? AND if it is the fuel pump relay is it possible to bypass it temporarily until we are able to buy a second relay (they are pretty challenging to find, and I am combing ebay as well).

Sorry if this has already been discussed, I didn't see any topics that answered my questions when I logged on. As well let me mention that we are not buying any of the parts that I mentioned above NEW. When I initially bought the car, my father had a fiat of the same make and model that was pretty beat up but drivable. And when I purchased this car he stripped that one of everything that was good in order to make sure that my car would last for a long while and so that it would drive well. My car came with a rebuilt engine and an iffy transmission, my dad's fiat had a good transmission and a rather poor engine so he took the transmission off and just put it on mine so that it would be as close to perfect as he could make such an... old/weird/faintly annoying car. So now that you have my full life story, could anyone help me out? Thanks! :)
vandor
Posts: 3996
Joined: Sat May 23, 2009 1:23 pm
Your car is a: 1971 124 Spider
Location: Texas, USA

Re: Fuel Pump Relay?

Post by vandor »

There should be only one fuel filter, someone must have added a second one on your car.

The fuel pump is turned on if the key is in the start position or if the AFM flap is open (ie. engine running).
So if the engine dies for any other reason, the fuel pump will loose power. It may not be dying because of the fuel pump - but then again it could.
As a test you could run a hot lead from the battery to the fuel pump and see if the car stays running.

The fuel pump relay is incorporated into the FI relay, it's called a 'double relay' or 'Mulitple relay' and most Fiat parts vendors carry them:

http://www.autoricambi.us/product/FI3-4 ... ple-Relay/
Csaba
'71 124 Spider, much modified
'17 124 Abarth, silver
http://italiancarclub.com/csaba/
Co-owner of the best dang Fiat parts place in town
So Cal Mark

Re: Fuel Pump Relay?

Post by So Cal Mark »

Csaba is correct, there isn't a "prime" position for the fuel pump. The engine should be cranking or running in order to get power to the pump. It sounds like you're bouncing around, hoping to stumble on a problem not sure if it's fuel or ignition related. First determine if you have fuel pressure or spark and go from there
linzy92

Re: Fuel Pump Relay?

Post by linzy92 »

I have checked fuel pressure. It's fine. I mentioned in my initial post that we do in fact have spark.
linzy92

Re: Fuel Pump Relay?

Post by linzy92 »

Got the car started. Ended up bypassing the relay completely. Car is running perfectly.
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