Technical Fuel injection relay

[Stavros83]

Hi .

I’m new to this forum and also to Fiat. I have owned some Alfa Romeos in the past and a lot of other brands but never a Fiat.

I have recently acquired a 1998/04 Barchetta. The fuel pump runs continuously on ignition and I can hear a loud swooshing noise in the rail. I have checked fuel pressure and it’s steady at 3 bar and but fuel pump will not cut off. The pressure valve in the rail is not leaking and no vacuum leaks anywhere.

Weirdly, if I leave the ignition on for a couple of seconds, the car won’t start, no spark. If I turn the ignition off and then turn to crank without stopping at ignition on, the car will start and sputter a bit until it settles on idle after 3 seconds.

My main problem is what seems to be misfires, small hiccups on idle but more violent jerking around 2000 rpm and light throttle. Car also feels a bit down on power.

I have changed the spark plugs - old ones were identical to each other and looked really good colorwise - and checked all connectors to all sensors. Exhaust is not smelly and no smoking.
No fault codes in ECU ( connector in passenger footwell) and no warning lights. Tried unplugging maf, idle control valve, throttle positioning sensors etc. Only negative impact. Checked Lambda which seems to alternate between closed and open loop as it should. Good live readings from all sensors.

I’m suspecting the big relay 7767970 on the firewall since fuel pump runs continuously on ignition but it seems impossible to find a new relay. Is there another OE number to use or will any other car brand OE work as a replacement?

Best wishes from Sweden

 

[bugsymike]

Hi .

I’m new to this forum and also to Fiat. I have owned some Alfa Romeos in the past and a lot of other brands but never a Fiat.

I have recently acquired a 1998/04 Barchetta. The fuel pump runs continuously on ignition and I can hear a loud swooshing noise in the rail. I have checked fuel pressure and it’s steady at 3 bar and but fuel pump will not cut off. The pressure valve in the rail is not leaking and no vacuum leaks anywhere.

Weirdly, if I leave the ignition on for a couple of seconds, the car won’t start, no spark. If I turn the ignition off and then turn to crank without stopping at ignition on, the car will start and sputter a bit until it settles on idle after 3 seconds.

My main problem is what seems to be misfires, small hiccups on idle but more violent jerking around 2000 rpm and light throttle. Car also feels a bit down on power.

I have changed the spark plugs - old ones were identical to each other and looked really good colorwise - and checked all connectors to all sensors. Exhaust is not smelly and no smoking.
No fault codes in ECU ( connector in passenger footwell) and no warning lights. Tried unplugging maf, idle control valve, throttle positioning sensors etc. Only negative impact. Checked Lambda which seems to alternate between closed and open loop as it should. Good live readings from all sensors.

I’m suspecting the big relay 7767970 on the firewall since fuel pump runs continuously on ignition but it seems impossible to find a new relay. Is there another OE number to use or will any other car brand OE work as a replacement?

Best wishes from Sweden

Is this any good.:-https://www.neobrothers.co.uk/car-parts/fuel-system/fuel-pump/oe-pump-control-module-relay-for-peugeot-citroen-4549-35

 

[Stavros83]

OE Pump Control Module Relay for Peugeot & Citroen 4549.35 - Car & Van Parts Specialists

Buy OE Pump Control Module Relay for Peugeot & Citroen 4549.35 at Low Price - Genuine Parts, OE Parts & Aftermarket Parts - FREE delivery available ✅ FREE click & collect ✅ Fast worldwide delivery ✅ Expert advice ✅

www.neobrothers.co.uk

Thanks. They seemed to list it as the same part as Fiat but no other sites do. I don’t know if there is someone who tried another OE number than 7767970 with success. Maybe I’ll be the first .

 

[bugsymike]

Thanks. They seemed to list it as the same part as Fiat but no other sites do. I don’t know if there is someone who tried another OE number than 7767970 with success. Maybe I’ll be the first .

If the part number matches and the seller confirms it should be OK, but I have never dealt with that seller so obviously at your own risk.

 

[Bartazar]

Wait, is the fuel pump not supposed to be on all the time? How else it supplying fuel?
I also always hear small electrical pump noise when driving coming from the back.

 

[bugsymike]

The whooshing noise could indicate air getting into the system, which although you are getting a good pressure reading does indicate some form of issue.
Is it possible the fuel pick up in the tank is perforated with rust?
Does a full fuel tank make any difference?
Is it possible to safely put the fuel outlet into a container of fuel and see if just clean fuel comes out or it has air bubbles when ignition turned on for a short time?
Is it possible a faulty injector is not shutting off, although when you inspected the spark plugs they were running clean and no other sign of running rich.
Can you pull plug leads one at a time to see if engine misfiring or weak on one cylinder re poor performance?

 

[Stavros83]

The whooshing noise could indicate air getting into the system, which although you are getting a good pressure reading does indicate some form of issue.
Is it possible the fuel pick up in the tank is perforated with rust?
Does a full fuel tank make any difference?
Is it possible to safely put the fuel outlet into a container of fuel and see if just clean fuel comes out or it has air bubbles when ignition turned on for a short time?
Is it possible a faulty injector is not shutting off, although when you inspected the spark plugs they were running clean and no other sign of running rich.
Can you pull plug leads one at a time to see if engine misfiring or weak on one cylinder re poor performance?

Yeah it sounds like air mixed in the rail. Never heard a rail sound like this before. Although neither have I experienced a fuel pump running continuously on key on ignition/engine off.
Since I got 3 bar confirmed pressure in the rail I didn’t think fuel was the issue.
I’ll order a new fuel pump assembly and new filter. The parts are quite cheap so worth a try.

Will measure all pins from ECU to relay holder this evening aswell. The relay clicks when key ignition is on but it never stops. Pump stops if I take out the relay so former owners haven’t connected the pump directly to ignition - everything is stock.

I did pull one coil at a time and no cylinder was reacting differently - I’ve dealt with bad coils in the past and usually the bad ones have less impact on engine when disconnecting.

 

[bugsymike]

Yeah it sounds like air mixed in the rail. Never heard a rail sound like this before. Although neither have I experienced a fuel pump running continuously on key on ignition/engine off.
Since I got 3 bar confirmed pressure in the rail I didn’t think fuel was the issue.
I’ll order a new fuel pump assembly and new filter. The parts are quite cheap so worth a try.

Will measure all pins from ECU to relay holder this evening aswell.

I did pull one coil at a time and no cylinder was reacting differently - I’ve dealt with bad coils in the past and usually the bad ones have less impact on engine when disconnecting.

I would try to check pump before replacing. For the pump to be working continuous, normally I would say they instructions it is getting are forcing it to do that via the relay or the pump was drawing air and having trouble maintaining the correct pressure.
Note, I did say instructions to the the pump as some vehicles keep a flow going to keep the fuel cool by circulating it around and back to the tank, but that wouldn't account for the "whooshing".
Maybe other Barchetta owners can advise regarding that?
If safe to do so, I would block the inlet pipe and then the outlet at the pump and see if it still tried to work continuously.
I did have a early diesel Fiat Doblo that relied on the "suction" of the Lucas Epic injector pump on the engine to draw fuel up and finally located the fault to the seal on the plastic push on fuel pipe at the tank to the sender/pick up unit. However in your case if a pump in the tank then any leak would be showing a fuel leak after that pump. If there was air getting in then it would have to be before the pump in the tank.
I have many times had spark plugs breaking down under load, but you have already changed them and no improvement.
Are you happy the injectors are functioning correctly?

 

[Stavros83]

The workshop manual states that the fuel pump should run for about 5 seconds to prime, then the ECU will release ground to relay and pump should stop. I don’t think it has any way of actually knowing what pressure the pump delivers. I think the pump has a 5 bar regulator and the regulator on the rail is 3.5bar.

Funny but the car drove great today for 20 minutes and started showing minor misfires after it got properly warm. So from cold it’s great, about 10-15celcius her today.
Maybe it’s the coils but the misfires are mostly idle and around 2000rpm with light throttle.

And I have a very noticeable smell of petrol when driving - even with the top down. Smells in the trunk aswell but nothing leaking in the engine bay och under the car. Maybe it’s the infamous vent seals on the tank. But the smell got worse when the car started to misfire. Have not yet read up on the gas canister recirculating hokus pokus system that’s fitted.

 

[bugsymike]

The workshop manual states that the fuel pump should run for about 5 seconds to prime, then the ECU will release ground to relay and pump should stop. I don’t think it has any way of actually knowing what pressure the pump delivers. I think the pump has a 5 bar regulator and the regulator on the rail is 3.5bar.

Funny but the car drove great today for 20 minutes and started showing minor misfires after it got properly warm. So from cold it’s great, about 10-15celcius her today.
Maybe it’s the coils but the misfires are mostly idle and around 2000rpm with light throttle.

And I have a very noticeable smell of petrol when driving - even with the top down. Smells in the trunk aswell but nothing leaking in the engine bay och under the car. Maybe it’s the infamous vent seals on the tank. But the smell got worse when the car started to misfire. Have not yet read up on the gas canister recirculating hokus pokus system that’s fitted.

Do you park on concrete? Any chance of fuel stains underneath to give a clue?
When you got the smell of petrol and engine misfire, was there any black smoke like running rich or like a car with choke out in the old days?

 

[Mike1alike]

About pump running, that is correct, ECU should cut electrical feed to pump after 5 seconds.
The rest, could be the filter before pump is very dirty so pump delivers pressure, but not flow. Instable fueling leads ECU to trimming the fuel, puts more in and that's why fuel smell can be felt, some unburned fuel is sent out through exhaust.
Also, running well cold and not well after heating up matches damaged pump. The electrical pump might not be at it's best anymore.

 

[tjr]

Hello @Stavros83,
Welcome, loads of great info here and knowledgeable members!

Perhaps perform the additional two fuel pressure checks to gain more info on the pump/fuel supply?
According to the service manual the pressure should be:
3 bar fuel pump on - engine off (this you already performed)
2,5 bar fuel pump on - engine on
5-7 bar fuel pump on - engine off - fuel supply to regulator off

Concerning fuel smell, these are unfortunately fairly common on the barchetta with several potential sources. Perhaps the most important one being a leak where the fuel hose/supply connects to (and from) the rail. Rumour has it that some barchettas have gone up in flames because of it. The b-95 (the barchetta I care for) had it to begin with (and has gone through two additional fuel vapour leaks).

Please let us know what you find and the solution to it.
All the best,
tjr

 

[Bartazar]

So the pump goes on for 5 seconds, then turns off if you haven't started the engine, then resumes operation once the engine has started?

 

[Stavros83]

Thanks @bugsymike @Mike1alike and @tjr for your replies.
@Bartazar Yes, that is correct. Mine does not turn off after 5 seconds with ignition on - engine off, which indicates a fault.

My friend came by an hour ago and wanted to check out the car. I took him for a drive expecting it to misfire and feel a bit restricted at the top end. To our surprise it ran great and felt more powerful than other drives. Came back and decided to take it for another spin since it ran so good. Nope, stutters and feels constricted again.

It´s bone dry underneath the car - no fuel or oil stains on the pavement.
The petrol smell is very apparent behind the seats so I´m guessing it´s the vent seals or something. I did check thru the fuel pump hatch but it was dry around the pump seal. Very smelly in there. I don't know if it's just different weather and winds that makes the fumes stay in the cabin on certain drives. I mostly drive with the roof down...

There are no leaks from the hoses in/out of the rail. I did actually check the fuel pressure with engine on as well. It stayed at 3 bar if I remember correctly. Did it at a friends place, maybe it´s time to do another check.

Could not find my multimeter so haven't gotten to measure the double relay connector to see if ECU tries to shut down the pump after 5 seconds.
I ordered a new fuel pump assembly and fuel filter today along with new ignition coils (already changed the plugs). Pretty cheap parts so why not..

I´ll post updates along the way.
Thanks!

 

[bugsymike]

It wouldn't account for the poor performance , but any chance fuel tank breather or filler pipe split?
I have seen fuel tanks rusted through at the top so only leak when full, but is yours plastic?

 

[tjr]

My friend came by an hour ago and wanted to check out the car. I took him for a drive expecting it to misfire and feel a bit restricted at the top end. To our surprise it ran great and felt more powerful than other drives. Came back and decided to take it for another spin since it ran so good. Nope, stutters and feels constricted again.

It´s bone dry underneath the car - no fuel or oil stains on the pavement.
The petrol smell is very apparent behind the seats so I´m guessing it´s the vent seals or something. I did check thru the fuel pump hatch but it was dry around the pump seal. Very smelly in there. I don't know if it's just different weather and winds that makes the fumes stay in the cabin on certain drives. I mostly drive with the roof down...

There are no leaks from the hoses in/out of the rail. I did actually check the fuel pressure with engine on as well. It stayed at 3 bar if I remember correctly. Did it at a friends place, maybe it´s time to do another check.

You are in contact with the ECU, which is excellent, but in what manner? The reason I’m asking is that with MultiECUScan (MES) you can monitor/record values in realtime (and save the data (and perhaps post it here for feedback)). MES can also perform some equipment/relay tests with ignition on - engine off. There is a separate section on the Forum on MES (in addition to the developer site w forum).

The b-95 is from 1995 so it may be different from yours (eg has a steel tank and an exterior fuel filter). The latest two leaks I had were at the tank, the gaskets were leaking between 1) fuel fill hose-tank connection and 2) fuel fill vapor exit hose-tank connection (passenger side). I added liquid gasket and new hose clamps, it’s been a few years on 1), and so far so good…
IMPORTANT! If/when you decide to address the fuel leak you may need to access the tank or extract it. The large access cover is behind the seats, and it is easiest to just disconnect the seats and lift them out BUT! be sure to disconnect the battery BEFORE! you start with the seats. Apologies for the theatrics, but many have activated the dreaded airbag light due to this, and several have had much trouble turning it off. There are several good threads on fuel tank access (and the airbag light). The fuel pump is accessed through a separate smaller cover. Does the fuel pump come with a new gasket, if not perhaps order one (with a little ”luck”, it’s the culprit)?

 

[Jarv1]

Hello!

New to the forum aswell, and got the same problem as you. Except that my fuel pump turns off after 5sec (got the gas smell as you do, changed seal at the top and its a bit better, its less smellt if you dont have a full tank of gas).

A bit rough idle and small hickups and really shaky/jerky around 2000rpm, when i add more throttle the problem seems to disappear. Gone through the same troubleshooting as you expect i dont have the obd, so a bit of shooting in the dark for me, cant see values and pressure...


What obd do you have?
Did the pump fix the problem?