Alfa Romeo Forums banner

1 - 11 of 11 Posts

·
Registered
Joined
·
10 Posts
Discussion Starter #1
I am a new GTV owner and encountered a strange, one time (so far!) performance issue. Driving on a hot day I suddenly lost power (like fuel starvation) and was barely able to make it home with a very rough ride. The next day I cranked it and it was fine (did leave a sooty deposit on the driveway after startup). The car starts quickly when cold but after warm up cranking is more difficult. I have the SPICA fuel injection. Any thoughts on where to start looking?
 

·
Registered
Joined
·
1,735 Posts
I would start at the easy to check items first, Fuel Filters, Ignition, Wires, etc... After all of that checks out 100% then keep digging deeper.
 

·
Premium Member
Joined
·
2,623 Posts
Is your fuel pressure light working? It should flicker on and back off when you first turn the ignition key. If it works and is flickering on and off while running, there's a good chance that your rear fuel filter is clogged. Carbon fouled plugs is another frequent culprit for rough running.
 

·
Registered
Joined
·
5,303 Posts
That era of Alfa's suffered with somewhat unreliable fuel pumps. It's a high pressure machine, totally external to the tank (later Alfa's had an internal pump. Remember that the fuel injection system recirculates fuel - the pump sends high pressure fuel to the injection pump, and returns excess fuel to the tank.

When the fuel level is low, the pump can overheat. For warm weather, be sure to keep your fuel level sufficient, and I'd predict you won't have this trouble again.

The "old school" solution was to carry a 24 to 30 inch length of broom stick to whack (well tap) on a stuck pump.

Robert
 

·
Super Moderator
Joined
·
11,365 Posts
I used to own Spica injected Alfas, and found that they were very susceptable to vapor lock. Warm day, fully warmed up car, < 1/2 tank of fuel were the conditions that would bring on the problem. I tried changing pumps, changing filters, heat shielding the fuel lines, rebuilding the Spica pump, .... you name it. Switching to Webers was the only solution that worked for me (I know the Spicanista don't like to hear that).
 

·
Senior TEXAS member
Joined
·
1,526 Posts
I used to own Spica injected Alfas, and found that they were very susceptable to vapor lock. Warm day, fully warmed up car, < 1/2 tank of fuel were the conditions that would bring on the problem. I tried changing pumps, changing filters, heat shielding the fuel lines, rebuilding the Spica pump, .... you name it. Switching to Webers was the only solution that worked for me (I know the Spicanista don't like to hear that).
Rancid, Sour, Hawg Trough Drippings, Sounds like just another excuse to change to carbs!!! ...:p;)

I have driven my '78 Spica Spider in South Texas Summers and NewMexico/ Utah deserts on way less than 1/2 a tank and have never had that issue or problem which you mentioned.
Remember, dont ever touch the accelerator ever, ever ever ever, on any startup, ever!
Realistically, you may be looking at a vapor canister/line problem or an improperly sealing gas cap.
 

·
Super Moderator
Joined
·
11,365 Posts
you may be looking at a vapor canister/line problem or an improperly sealing gas cap.
Oh thanks for reminding me - yea, I tried that too. Pulled the circular gasket out of my gas cap, so it's fit wouldn't be air tight. No luck there either.

Look my intent here isn't to criticize the Spica system. If you guys like it, more power to you. I'm just pointing out that many Spica owners have reported the vapor lock problems that timpyran is experiencing. Has anyone found a fix for it? I certainly never did.
 

·
Registered
Joined
·
5,303 Posts
Technically it can't be vapor lock in the traditional sense. This condition is unique to engine mounted suction pumps, where the fuel temperature is high enough that the suction from the pump is above the vapor pressure of the fuel, causing cavitation in the fuel like - an air (actually fuel vapor, not air) gap in the fluid flow.

Because the SPICA system uses a high pressure pump (around 100 psi AFAIK), this condition is impossible. The fuel is under pressure from the rear pump to the SPICA unit, and back thru the return plumbing. The only suction occurs between the tank and the rear pump, which is why Alfa eventually moved the pump into the tank.

What does occur it that the circulating fuel absorbs engine heat, slowly raising the tank fuel temperature. In the vapor-recovery fuel system, this can occasionally result fuel getting into the vapor lines, blocking its proper operation. It also heats up the high pressure pump, which was not designed for such; as it heats, the magnetics are affected and the pump slows and sometimes jambs.

In the mid 70's, John Shankle made a small (about 3 by 3 inches!) cooler that went in the fuel return line. Problem solved for my Alfetta! Looked like a section of refrigerator cooling to me. You could also try an air duct aimed at the SPICA pump. It gets as hot as the engine, which is where the fuel gets heated from.

If you put a temperature probe in the fuel tank, you can actually watch this happening, and see the temperature that the pump starts to fail. You'll be amazed at how hot the fuel gets! The fuller the tank is the longer it takes to get "too hot".

Robert
 

·
Registered
Joined
·
4,264 Posts
I am a new GTV owner and encountered a strange, one time (so far!) performance issue. Driving on a hot day I suddenly lost power (like fuel starvation) and was barely able to make it home with a very rough ride. The next day I cranked it and it was fine (did leave a sooty deposit on the driveway after startup). The car starts quickly when cold but after warm up cranking is more difficult. I have the SPICA fuel injection. Any thoughts on where to start looking?
The very first thing I'd do is the easiest. It sounds like your fuel filter is clogged. Actually, clogging is the better word because a filter that needs changing will behave exactly the way you're describing what happened to you. The car will start and run just fine, then it won't. Let is rest awhile and it'll start and run and then it won't. This goes on until it won't start at all. (If this happens, tapping the outside of the fuel filter housing may sift the sediment around and let you get going again. For awhile, anyway.)

My back-in-the-day solution is this:

Changing a fuel filter (at the back of the car near the tank) is very easy and you can do it in your driveway. Just make sure you have something to block the fuel line coming from the tank (I used an appropriatedly sized phillip's screwdriver but a golf tee or round pencil will also work). Try that before you do anything else. With a car this old it's lunlikely that it has it's original fuel pump, but if it does think about changing to a new one.
 

·
Premium Member
71 Berlina 74 GTV 17 Giulia Q4
Joined
·
6,568 Posts
I'd also suggest reading up on the theroy and operation of the system, knowledge is power:)
 
1 - 11 of 11 Posts
Top