Fuel Pressure Light On!

[cdornier]

Well, I've re-established my account, after the big crash. So, John, (or anyone else who cares to comment!), my '76 Spider is running great. But, now, as of this evening, the fuel pressure warning light comes on. Specifically, it comes on during hard acceleration, and also comes on at idle, after the car is well warmed up. When it comes on during hard acceleration, the car displays no symptoms of being fuel-starved (i.e., smooth acceleration with no sputtering). Soooo... what does this mean? Remember, I have little mechanical experience with Alfas! Thanx-

[Roadtrip]

Mark - Could be a couple of problems. First, make sure the wire to the low pressure sensor on the front fuel filter isn't grounding against something causing a false light.

1. When was the last time the rear fuel filter was changed? A clogging rear filter is the usual suspect. If it is becoming clogged, an inspection of the interior fuel tank is indicated. Change the rear fuel filter and see if that has affect. If you don't know when the front filter was changed last, I'd change that one too.

2. If the rear filter is good, then it's likely a failing fuel supply pump. Your year car should have an old 3 port model, if it's original. The best substitute for it is the new Bosch 2 port for the L-Jetronic cars. It takes a small bit of mod to fit it in a SPICA car, but nothing hard.

Do you have the guide to the Fuel Supply System I wrote? If not, PM your email address and I'll send it to you. It should answer all your questions.

[cdornier]

As I just acquired the vehicle, I'm not sure if or when any of the fuel filters have been changed. Anyhow, the included service record mentions nothing of fuel filters. So I will start with your suggestions.

Yes, I would be most interested in reading your Fuel Guide. I will send you my e-mail address shortly.

[Roadtrip]

Mark - Post some pictures of the car. Like to see it.

Hopefully it's just a clogging rear filter. If the fuel supply pump is original, it's likely the culprit. Those pumps are going on 30 years old now, so you've got to expect them to fail.

[cdornier]

Well, actually, you saw my car already (remember, this is the blockhead who dropped the washer into his fuel injection pump?), but here it is again:

[Roadtrip]

Yes, I remembered, but when I went back to look at the previous posts they were casualties of the great server crash in May. There's been so many people with SPICA questions that sometimes they run together in my memory. Glad to hear the spring fix is staying good. Now to just get the fuel supply back up to snuff. The problems you're running into are perfectly normal and not unusual for a 30 year old car, so don't get frustrated.

That's a really nice Spider. Is the interior as good as the pristine exterior?

Take a look at your present fuel supply pump up near the right rear wheel well and let me know what kind it is. The guide I sent you has pictures of the various types. I'm guessin' its the old 3-port on one end model. If so, it's likely that it's going bad on you. The flashing low pressure warning light at idle (lower voltage to pump) and under engine load (high fuel demands) are typical of a failing pump. However, that said, it's also very likely it could be a clogged rear fuel filter. If we're still getting a low pressure warning light after a filter change, then it's time to stare at the supply pump.

I don't think it's likely, but does your car have an in-tank boost pump as described in the diagnostics guide? Also, does the feed line from the tank to the fuel supply pump come out the top of the tank and not the bottom?

As an added note, since the car is new to you and if you don't know when the fluids were last changed, I'd go ahead and change the transmission oil , differential oil, and coolant, as well as get it a real good steam/pressure wash cleaning in the engine compartment and underside (beware that you'll have to sop up the pools of water around the spark plugs afterwards or it won't start). I'd also do a compression test and record the numbers for future reference. It's so much easier to work on a nice clean engine. It looks to me like the car was well taken care of by the PO. Usually with cars that look that good, it means the PO took care of them mechanically as well, but you really want to baseline it maintenance-wise anyway. I think you found a really good example to buy.

Let me know if a filter change has any affect on the fuel low pressure warning light.

[cdornier]

Quote:

Originally Posted by Roadtrip ... That's a really nice Spider. Is the interior as good as the pristine exterior?

[Farace]

Quote:

Originally Posted by cdornier So now that you know the story, you still think so? I look at the car and think maybe $4000 (after repairs) is not really that great a deal, but then again, I've been out of the Alfa loop for a good 15 years, and am likely a little disconnected with the real value of these cars. Maybe I've just gotten to be a cheap you-know-what in my old age.

[cdornier]

Quote:

Originally Posted by Roadtrip ... Let me know if a filter change has any affect on the fuel low pressure warning light.

[boggissimo]

Quote:

Originally Posted by cdornier Overall not bad, but the rubber floor coverings are a little aged, and the seats have a few rips, and are currently covered with the IAP slip covers. Someone did carve speaker holes into the console sides, but I have fashioned some circular covers. Tha car was painted once, but back to its original silver. It just had a mess of work done to it before I took delivery, including a valve job, head gasket, coolant flush, brake pads, water pump, slave cylinder, u-joints, and heater hoses. I paid $2700. The I turned around threw in another $1200, having my mechanic kinda go through it, and fix a bunch of stuff that needed attention, like the seized heater blower fan, the unhooked console lights, the horn, the flakey ignition switch, wiper switch, and a few other things, as I did not have the time to fix these myself. After shopping for a while and seeing the skows that were touted as "excellent condition" by delusional owners, I concluded it was more important to find an example with an intact, straight, and unrusted body, and the mechanicals were a secondary consideration.

[Roadtrip]

Glad to see that the filter change seemed to do the trick. However, if you got a low pressure warning light at full accel (big fuel demand) and idle (low voltage), if your fuel supply pump is old, it's likely that it's giving you fair warning of failure. Old pumps will work fine for a while, then give you intermittent low pressure lights, then really go bad very quickly, or blow a fuse. I heard of one guy that shorted the fuse "to get home" on a supply pump that was starting to draw excessive current. Could have been a contender for a Darwin Award.

My advice would be to have a spare pump at the ready (in the trunk), or better still, R&R it now and save the old pump as an emergency spare.

[gdl1952]

I just acquired a 74 Spider and I am reading this thread with interest, since I also am experiencing the intermittent on/off fuel pressure light, which stayed on continuously during my drive to my garage after I just bought it.
Mr. John Stewarts’ guide to the fuel supply system would indeed be very helpful – a thanks in advance plus an invite to stop by my place next time in Napa for some custom made wine tasting.
I am just about to order parts form Centerline (they appear to be quite knowledgeable and not too expensive), and that order will include both fuel filters, plus tune up parts, oil filter, etc. – namely what needed to ensure that the car is serviced properly at the get-go. Further plans include fixing the floor panels, rebuilding the front suspension and possibly switching to Webers (this is my second Alfa with Spica and my first one, a 1300 GT had a beautifully-sounding Dell’Orto…).
Saluti.

[Roadtrip]

Gianni - If you want a copy of the fuel supply diagnostics guide, PM me an email address.

John

[gdl1952]

Thanks John: please e-mail to:
gdl1952@yaoo.com
Take care,
Gianni

[DavidB]

John - can you shoot me copy of the diagnostic guide (dmburroughs@earthlink.net). Our Alfa club had a joint tour with the local Triumph club last Sunday and racing around the pressure light began to come on during hard acceleration, hill climbing or hard cornering cornering (once I though I smelled gas but never again) but not at idle. The fuel tank was full. The tank "pusher" pump was done last year and the filters only have 1,800 miles on them and were done last year.
Thanks,