Stupid Question That I should know the answer to

1215 Views 10 Replies 6 Participants Last post by radibob, Oct 22, 2007

radibob

Discussion Starter · Oct 15, 2007

Ok here goes. Still struggling with fuel pressure issues as in a flickering FP light at speed. New pump, most hoses, filters, restricted the outlet on the return pipe as directed, made sure the tank vent is working etc etc. Last week I cleaned all of my fuses and replaced another hose that looked like it might be ever so slightly kinked. Took the car out (running great)and it was fine till it got warm and I did fill the gas up, then it was worse. The light was even flickering with the engine off and the ignition on. I checked for gas leaks and there were none

So I got under the car with the ignition on and put a multimeter on the positive terminal of the pump and grounded the other and I got 9 volts (again with the pump, not the car, running)
So the stupid question is whether even with the pump running should I get 12or better volts. My belief is that I should.
(This is driving me nuts)

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Alfar7

· #2 · Oct 15, 2007

Voltage at pump

You are correct it should be same as battery voltage.
A primary problem in older Spica cars is the small alternator. A swap to a later model, Spider,GTV6, Milano type with internal regulator is a good upgrade. If a show car leave external regulator with wires cut off below & hidden in harness.
You need to check the ground on the pump, an additional ground at the site might solve the problem. If not, trace back that power wire & clean all connections.
If ground does not do it, try this as a test. Run a long jumper wire (14gauge) from the battery & turn on pump , listen to sound. While it is running touch the jumper to the pos terminal on pump. If speed increases you have confirmed a wiring problem.
Rj

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twoliterlover

· #3 · Oct 15, 2007

Fuel Pressure{

Change the filter in the rear.

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144

· #4 · Oct 16, 2007

Yes, you need to find out where the voltage drop is and fix it.

Also, what supply pump is in the car now and did you narrow the outlet restrictor on the injection pump outlet fitting.

Do you have the Diagnostics Guide at www.wesingram/hp.htm?

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radibob

Discussion Starter · #5 · Oct 16, 2007

Status

Well thanks for all of the excellent replies.
The pump is from Centerline, not sure of the brand. I did restrict the return opening.
In the next few days I am going to remove the wiring on the pump and check it out for voltage and ground and then replace both filters (which have less than 1000 miles on them, but who knows).
We'll see where that gets me.
I think initially this was a multi faceted problem, probably first caused by a plugged tank vent, now fixed. Maybe when I replaced the pump which was noisey, I screwed up the wiring or whatever. I had to solder new terminals on both so I need to check that.
The cars runs great but I don't want to drive it with the light thing flickering.
Thanks again.

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yvesmontreal

· #6 · Oct 17, 2007

to pump or not to pump

radibob said:
Well thanks for all of the excellent replies.
The pump is from Centerline, not sure of the brand. I did restrict the return opening.
In the next few days I am going to remove the wiring on the pump and check it out for voltage and ground and then replace both filters (which have less than 1000 miles on them, but who knows).
We'll see where that gets me.
I think initially this was a multi faceted problem, probably first caused by a plugged tank vent, now fixed. Maybe when I replaced the pump which was noisey, I screwed up the wiring or whatever. I had to solder new terminals on both so I need to check that.
The cars runs great but I don't want to drive it with the light thing flickering.
Thanks again.

The 9 volts is definitely not normal and should be fixed before it leaves you stranded with 0 volts. But if the car runs fine, perhaps the Spica pump is getting enough fuel anyway and the light is flickering because it is defective on its own.

Try removing the pump fuse and see what the light does - it should be solidly on.

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radibob

Discussion Starter · #7 · Oct 18, 2007

latest news

Spent last night under the car. I was there so long my wife came out and shut the lights off thinking I had gone to bed.
Anyways the wiring at the pump reads 11.5 volts with the standard ground and with a local ground. This is with the car not running obviously. Not sure if I really need that extra half volt to run the pump at full capacity.

More interestingly while I was done there I replaced the rear filter. Its about 2-3 years old but not much mileage since I've been busy with other things (like work) so lets say 1-2 thousand miles. Anyways once I had it off I tried to blow through it to see if it was clogged. It was wet with gas but was pretty hard to get any air through like the same resistance you might get with blowing up a balloon. Even wet with gas this didn't seem right, so we'll see if that is the problem. Do these typically clog that fast?

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Alfacliff

· #8 · Oct 18, 2007

that depends on amountof rust in the gas tank. Check for good ground by measuring from - term of battery to body with lights on. should be less than .1 volt. check from gas tank to body with pump running, should be very little voltage, less than .1 volt. grounds in Alfa's and all older cars are subject to corrosion which limits current.
cliff

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radibob

Discussion Starter · #9 · Oct 18, 2007

Ground and gas tank

I did check and clean the engine ground for what that is worth. The battery ground was also cleaned (but will do it again). I was looking at the gas tank while under the car and wondered if it was aluminum? I do keep it filled to avoid rust but after 30 years who knows. Do people routinely flush these?

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Alfacliff

· #10 · Oct 18, 2007

the gas tank is coated steel, not sure if it is galvanized or something else. I have not had to flush my tank yet, but some people do.
cliff

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radibob

Discussion Starter · #11 · Oct 22, 2007

The answer to fuel pressure problems

The answer to the fuel pressure deal was the rear filter. Not many miles on it but a few years so gas tank debris caught up with it .
The lesson for me is to change it every year no matter what the miles.

Thanks for the help. its running very well now.

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