Hi,
the Alfa 90 just died yesterday. It ran in the morning and then my wife could not restart it.
I believe it is the fuel pump. Following the suggestions previous post's on the topic in the old forum, I dissconnected the AFM from the rubber intake, turned on the ignition and depressed the vane inside the AFM. I can hear the relay for the fuel pump click, but can not hear any whirring that would sound like the fuel pump is running. I dissconnected the fuel line directly in front of the housing to see if any fuel would pump out, but none does.
So my assumption is this:
1. My fuel pump is bad
2. The electrical connetion to the fuel pump is bad
(I didn't have my DMM to check the electrical connection)
My question is this. Normally if I perform the above procedure, should I expect to 1. hear the fuel pump and 2. see fuel comming out.
The answer seems obvious, if I understood the correct operation of the fuel relay.
Cheers,
Marco
Fuel Pump
You are correct on both counts. The pump will run and if you open the fuel injection manifold, fuel will be pumped out. You can test the wiring with a 12v bulb, a parking lamp bulb perhaps. You can also test the pump by getting 12 volts directly to it. I would disconect the (+) side if you try this in car just to be sure nothing happens to the L-Jet box.
Scott Shure
Ellicott City, Md
85 GTV-6
Ellicott City, Md
85 GTV-6
Hi shures,
thanks for the reply.
Just checked the pump. There is voltage at the pump, and I can hear the pump whirring (very quietly).
However, when I dissconnect the fuel feed (This is the fuel line feed directly in front of the plenum) I see no fuel comming out. Am I checking the wrong fuel hose?
Marco
thanks for the reply.
Just checked the pump. There is voltage at the pump, and I can hear the pump whirring (very quietly).
However, when I dissconnect the fuel feed (This is the fuel line feed directly in front of the plenum) I see no fuel comming out. Am I checking the wrong fuel hose?
Marco
Marco
1985 Alfa 90
1985 Alfa 90
Marco, just to clarify, the fuel enters the fuel rail at the "back" bulkhead end of the engine, the fuel returns to the tank from the "front" bonnet end of the engine.
If the "rear" is disconnected fuel should pour out of the instant the pump runs. If you disconnect the front it'll still come out, but only after a second or so delay once the fuel rail has pressurised.
You must isolate the fault to the pump or otherwise. If you can hear the pump making a noise & don't get any fuel flow then probably the pump isn't delivering at all. Either it's blocked, maybe gummed up, or a lump of something solid has somehow gotten in, or the fuel line is blocked (perished, collapsed, crushed), or there's hardly any electrical power getting there.
If there's no fuel at the engine comparment, test voltage at the pump when it should be runing. If OK disconnect at the outlet of the pump and try it again - beware LOTS of fuel will come out if the pump works. If no flow then try reversing the wires and running it backwards for a few seconds, it might clear itself ?
Other than than I guess you're looking at a replacement pump.
Obviously there is a big potential FIRE HAZARD with raw fuel squirting out as you do any of this. Take all appropriate care.
hope you solve the problem
If the "rear" is disconnected fuel should pour out of the instant the pump runs. If you disconnect the front it'll still come out, but only after a second or so delay once the fuel rail has pressurised.
You must isolate the fault to the pump or otherwise. If you can hear the pump making a noise & don't get any fuel flow then probably the pump isn't delivering at all. Either it's blocked, maybe gummed up, or a lump of something solid has somehow gotten in, or the fuel line is blocked (perished, collapsed, crushed), or there's hardly any electrical power getting there.
If there's no fuel at the engine comparment, test voltage at the pump when it should be runing. If OK disconnect at the outlet of the pump and try it again - beware LOTS of fuel will come out if the pump works. If no flow then try reversing the wires and running it backwards for a few seconds, it might clear itself ?
Other than than I guess you're looking at a replacement pump.
Obviously there is a big potential FIRE HAZARD with raw fuel squirting out as you do any of this. Take all appropriate care.
hope you solve the problem
83' GTV6, 3.0 24v supercharged
Steve,
thanks for the clarification. It definitely is the fuel pump. I connected 12V directly to the pump and you can hear it click but not run. I think I have to check my ears because yesterday it sounded like it ran. This explains why I am not seeing any fuel at the regulator.
Measuring the voltage with my trusty Fluke DMM, the voltage at the pump was 7.41V. It would be interesting to know what the voltage is for a correctly operating pump. I just want to clarify the significance here. With a direct jumper connection resulting in very low Ohmic losses, it appears that the fuel pump is loading the battery to an extent that battery voltage is dropping quite dramatically here. This 7.41V reading is exactly the same as when I measured it with out jumpering to the battery which to me indicates that there was very little loss in the car wiring itself. At the very least, this test will indicate how good or bad a supply circuit is.
Will now source a new pump.
Thanks for all your help.
Cheers,
Marco
thanks for the clarification. It definitely is the fuel pump. I connected 12V directly to the pump and you can hear it click but not run. I think I have to check my ears because yesterday it sounded like it ran. This explains why I am not seeing any fuel at the regulator.
Measuring the voltage with my trusty Fluke DMM, the voltage at the pump was 7.41V. It would be interesting to know what the voltage is for a correctly operating pump. I just want to clarify the significance here. With a direct jumper connection resulting in very low Ohmic losses, it appears that the fuel pump is loading the battery to an extent that battery voltage is dropping quite dramatically here. This 7.41V reading is exactly the same as when I measured it with out jumpering to the battery which to me indicates that there was very little loss in the car wiring itself. At the very least, this test will indicate how good or bad a supply circuit is.
Will now source a new pump.
Thanks for all your help.
Cheers,
Marco
Marco
1985 Alfa 90
1985 Alfa 90
Hi Dave,
Good point.
I will measure the fp terminal resistance.
also I will measure the voltage at the battery terminals themselves. If it remains at approximately 12V then I know there is a signficant voltage drop accross the jumper wires I am using. I'll also measure the current.
My new fuel pump is comming in, so I'll compare the resistance measurements.
Will report back shortly
Marco
Good point.
I will measure the fp terminal resistance.
also I will measure the voltage at the battery terminals themselves. If it remains at approximately 12V then I know there is a signficant voltage drop accross the jumper wires I am using. I'll also measure the current.
My new fuel pump is comming in, so I'll compare the resistance measurements.
Will report back shortly
Marco
Marco
1985 Alfa 90
1985 Alfa 90
FYI
Made the following measurements
No load voltage at battery terminals: 12.3 V
Loaded battery voltage: 11.6V
Resistance of jumper leads from battery to fuel pump: 0.6 Ohms
Voltage measured at fuel pump: 7.41V
Current to fuel pump = (11.6 - 7.41) / 0.6 = 7.98A
So the fuel pump in the "stuck" state is drawing a fair bit of current but not enough to blow the fuse. The winding resistance was measured at 1.3 Ohms which I have nothing to compare to. Regardless the fuel pump tries to turn but is jammed hence the reason it draws so much current.
This explains the low voltage measurement at the fuel pump terminals. Even a small resistance of 0.6 Ohms will create a significant voltage drop if the current is high enough.
Marco
Made the following measurements
No load voltage at battery terminals: 12.3 V
Loaded battery voltage: 11.6V
Resistance of jumper leads from battery to fuel pump: 0.6 Ohms
Voltage measured at fuel pump: 7.41V
Current to fuel pump = (11.6 - 7.41) / 0.6 = 7.98A
So the fuel pump in the "stuck" state is drawing a fair bit of current but not enough to blow the fuse. The winding resistance was measured at 1.3 Ohms which I have nothing to compare to. Regardless the fuel pump tries to turn but is jammed hence the reason it draws so much current.
This explains the low voltage measurement at the fuel pump terminals. Even a small resistance of 0.6 Ohms will create a significant voltage drop if the current is high enough.
Marco
Marco
1985 Alfa 90
1985 Alfa 90
Fuel pump
Marco,
If you are considering a replacement pump, check out the main unit from and old Volvo 240 GL. They are tough as nails and have lots grunt. You wil need to change the mount a little but it could save some bucks in the process. I say could but I am not familiar with your local prices..
If you are considering a replacement pump, check out the main unit from and old Volvo 240 GL. They are tough as nails and have lots grunt. You wil need to change the mount a little but it could save some bucks in the process. I say could but I am not familiar with your local prices..
Transaxle Alfas Haul More Arse
MD,
I'll take a look at the volvo pumps.
new bosch fuel pumps for Alfa GTV's, 75 and 90's are going for $160.00Aud, which really is not that bad after comparing to U.S prices which are about the same in U.S currency. So they are actually cheaper here.
I'm actually going to go with a used unit for $20 Aud, I probably shouldn't but I'm willing to take a chance here.
Thanks guys for the input
Cheers,
Marco
I'll take a look at the volvo pumps.
new bosch fuel pumps for Alfa GTV's, 75 and 90's are going for $160.00Aud, which really is not that bad after comparing to U.S prices which are about the same in U.S currency. So they are actually cheaper here.
I'm actually going to go with a used unit for $20 Aud, I probably shouldn't but I'm willing to take a chance here.
Thanks guys for the input
Cheers,
Marco
Marco
1985 Alfa 90
1985 Alfa 90
IT LIVES!!!
Put the new fuel pump in, checked operation, started her up and away she went.
Measured the voltage at the terminals and got 10.8 V for a current of (11.9-10.8') / ~1Ohm = 1.1A where 11.9 is the voltage measured at the battery terminals when the car is not running and ~1 Ohm is the estimated circuit resistance.
In summary, my symptoms were:
Starts runs for 1-3 second, then stops. After 3 or 4 times it would not even run, since the injection system was completely starved of fuel. My troubleshooting method was to:
1. Check to make sure I had spark (used a timing light)
2. Check to make sure the fuel relay was functional by manually operating the AFM vane
3. Check to see if the fuel pump ran and actually supplied fuel pressure.
Cheers,
Marco
Put the new fuel pump in, checked operation, started her up and away she went.
Measured the voltage at the terminals and got 10.8 V for a current of (11.9-10.8') / ~1Ohm = 1.1A where 11.9 is the voltage measured at the battery terminals when the car is not running and ~1 Ohm is the estimated circuit resistance.
In summary, my symptoms were:
Starts runs for 1-3 second, then stops. After 3 or 4 times it would not even run, since the injection system was completely starved of fuel. My troubleshooting method was to:
1. Check to make sure I had spark (used a timing light)
2. Check to make sure the fuel relay was functional by manually operating the AFM vane
3. Check to see if the fuel pump ran and actually supplied fuel pressure.
Cheers,
Marco
Marco
1985 Alfa 90
1985 Alfa 90
-
twinspark6
- Gold
- Posts: 80
- Joined: Thu Dec 23, 2004 9:07 pm
- Location: san francisco