Alfa Romeo Forums banner

1 - 13 of 13 Posts

·
Registered
Joined
·
59 Posts
Discussion Starter #1
I just purchased a 84 spider that is not running. Previous owner said it "just died".
I've checked the spark which is strong.
I've check the pulse to the injectors with a "node" and there is a pulse.
I listened and felt the relay when turning on the car and there is a definite "click" BUT no sound of a pump running.
How do I check fuel pressure to the rail?
How can I test the relay to make sure it is working?
Thanks
 

·
Administrator
Joined
·
16,341 Posts
Remove the hose to the Cold Start Injector and put in a tee to attach a fuel pressure gauge. (the manual says to tee into the fuel inlet hose)
 

Attachments

·
Registered
Joined
·
59 Posts
Discussion Starter #3
Thanks for the info. Since I can't start the engine I'm looking for pressure from the pump to the rail. Do you think this method will work if there is no engine running?
 

·
Registered
Joined
·
7,260 Posts
to see if fuel is coming up to the rail....remove the fuel hose entering the rail and have someone crank the starter.... have some rags handy
if fuel is coming then maybe check the fuel pressure regulator.....pull off the small vacuum hose and if you see signs of fuel in the hose, the FPR is bad.

if you suspect the big fuel relay (aka: drive relay), jump the relay plug at #30 & #87: the pumps should run.
 

·
Administrator
Joined
·
16,341 Posts
...if you suspect the big fuel relay (aka: drive relay), jump the relay plug at #30 & #87: the pumps should run.
Just wanted to add - the above is for testing purposes only. The drive relay also acts as a safety device in the event of an accident. If the engine stalls a properly functioning drive relay will cut power to the fuel pumps.

Which reminds me - Series 3 Spiders up to '84 or '85 also have (had?) an inertia fuel pump shut off device. In the event of a crash it would cut power to the fuel pumps. This switch proved problematic - sometimes it would cut power after a bump in the road (or maybe even for no reason...). Alfa then decided the drive relay would function as a safety device making the inertia switch redundant. Check your car for an inertia switch. It is either a small can shaped or cigarette pack size rectangular shaped device with a button on top located on the firewall near the hood latch. The button is to reset it. Even better is to bypass it - connect the two wires attached together (then wrap them with electrical tape to avoid short circuits). This is exactly what Alfa did with the later models - they didn't change the wire harness - just connected the wires together and buried it in the wire harness.

Here's a photo of the rectangular one:


And the can shaped one:
 

·
Registered
Joined
·
59 Posts
Discussion Starter #7
Yeah...this car has the black box with the rubber cover. I did test it and the button was "IN".
But I will bypass it. Thanks again.
 

·
Registered
Joined
·
59 Posts
Discussion Starter #8
OK...when I jump 30/87 there is a muffled single "thump" from the pump.
Shouldn't it "whirrr or hummm" as long as the plug is jumped and it gets power....or is there a pressure cutoff?
 

·
Administrator
Joined
·
16,341 Posts
Shouldn't it "whirrr or hummm" as long as the plug is jumped and it gets power...
Yes.

or is there a pressure cutoff?
Nope.

Check the electrical connections to the pump (the main pump, under the car). Remove, clean & make sure they are secure. IIRC, they are slightly different sizes for + & - but be careful you don't mix them up. How much gas is in the tank? There is also an in-tank pump (in the tank...) to ensure the main pump gets a steady supply of fuel - especially when the tank is below 1/2 full.

There is also a fuse for the fuel pumps. It is located under the parcel shelf behind the seats - next to the FI computer. The original fuse is a 'bullet' type. These are known to somehow look OK but still fail to pass electrons. The bullet fuse with a brass strip is better then the ones with an aluminum strip. Even better is to remove the old fuse holder and install one that takes a blade type fuse. 8 amps is the correct size.
 

·
Registered
Joined
·
59 Posts
Discussion Starter #10 (Edited)
OK...I have checked the "bullet" fuse and it tested Ok but I like the idea of replacing it with a blade fuse.
The tank is just at or slightly below 1/2.
I will top it up but how critical is the full level?
What happens under normal conditions as the tank drops below 1/2?
Where does the tank pump draw fuel from...only 1/2 way down the tank?
Is there any gravity component taking fuel from the tank to the injector pump?
If the in-tank pump fails does that cause the car to die?
How can I test the in tank pump?
Does the pump relay command both pumps?
I've spent my life in aviation and this seems like a pretty bad design for fuel delivery.
Strange system... generates lots of questions.
I appreciate your experience with this system and any guidance on it's operation..
 

·
Premium Member
Joined
·
13,050 Posts
I have retained the inertia switch on my GTV6 as an anti-theft device.
 

·
Administrator
Joined
·
16,341 Posts
I will top it up but how critical is the full level?
If everything is working correctly not critical. But read on...

Where does the tank pump draw fuel from...only 1/2 way down the tank?
The pick up is at the bottom of the tank. But (why is there always a but...), if the in-tank pump is not functioning then then main pump has a hard time drawing fuel up & out of the tank. And, to complicate it further, there is a special 'stepped hose' connecting the in-tank pump to the outlet pipe (still inside the tank). If the stepped hose is faulty then, when the fuel level drops below ~ 1/2 full, the main pump will suck air. Since fuel is used to both cool and lubricate the main pump, this air can be detrimental to the main pump.

If you price out the stepped hose be sure you are sitting down...



If the in-tank pump fails does that cause the car to die?
Maybe.

How can I test the in tank pump?
Usually if you can hear it run it is working. You can disconnect the outlet hose from the in-tank pump and jump 12V to the fitting on top of the tank and observe if fuel is pumped.


White w/black trace is low fuel light
Pink w/white trace is pump power
Purple is fuel amount
Black is pump ground


Does the pump relay command both pumps?
Yes, they are wired together.
 

·
Registered
Joined
·
59 Posts
Discussion Starter #13
Very informative...thank you.
What is the part number for an acceptable Bosch pump or is there a less expensive alternative??
The Bosch number on this one is 0 580 464 020 and I'm pretty sure it is the original.
Also, how do I drain he tank??
I pulled the feed line off the pump ( the inlet from the tank) but nothing. I suppose the in tank pump is stopping the flow.
 
1 - 13 of 13 Posts
Top