R4 F4 fuel pump

[Rustyoldjcb]

Hi!

I was wondering whether the very poor running of my engine, especially at idle, was due to the fuel delivery system. The fuel pump doesn't appear to match anything in the Haynes manual, so I dont know if it is correct for a 1987 F4? Although it must have run ok on it in the past.





I disconnected the fuel line on the outlet of the pump and cranked the engine. Plenty of fuel came out. I partially blocked the outlet and could hardly feel any pressure when cranking. How much pressure should there be?

Going to blow the fuel line back towards the tank to see if its clear.

Thanks!

 

[Rustyoldjcb]

Well I blew the fuel line through, just as SWMBO was passing, and got an earful (not of petrol!). So that's clear. Started her up and she fired immediately, which makes me think the pump could be ok. But she still runs rougher than a Roughy Mc Rough Face. Still curious as how much pressure a fuel pump should deliver.

 

[Andy McGhee]

Have you checked the arrowed hose in the photo? If the end that goes into the manifold has fallen off, or if the restrictor inside the hose is blocked, you'll get really bad running problems.

 

[laxeian]

Had problems on mine with intermittent tickover problems, eventually found it was the rubber fuel lines themselves between chassis to pump, pump to carb, visually they looked fine, could still read makers ink etc, did not notice problem to start with, assumed petrol smell was flooding when hot etc., but with the engine warmed a little cracks and slight leaks could eventually ( after a period of non-use) be seen/felt, typically it was on the side of the pipes not visible to the eye, the engine block side, your pipes in photo do look like they are a little distorted shape wise but suppose we all do when we reach the age of our 4’s

 

[Rustyoldjcb]

Have you checked the arrowed hose in the photo? If the end that goes into the manifold has fallen off, or if the restrictor inside the hose is blocked, you'll get really bad running problems.


View attachment 26665

Thanks for that, I'll check it out.

 

[Rustyoldjcb]

Had problems on mine with intermittent tickover problems, eventually found it was the rubber fuel lines themselves between chassis to pump, pump to carb, visually they looked fine, could still read makers ink etc, did not notice problem to start with, assumed petrol smell was flooding when hot etc., but with the engine warmed a little cracks and slight leaks could eventually ( after a period of non-use) be seen/felt, typically it was on the side of the pipes not visible to the eye, the engine block side, your pipes in photo do look like they are a little distorted shape wise but suppose we all do when we reach the age of our 4’s

Thanks! Worth checking out for sure!

 

[Rustyoldjcb]

Still like to know if anyone can confirm if I have a 'proper' fuel pump and what sort of pressure it should deliver.

 

[angel]

A "proper" fuel pump for a carburettor is one that can fill the float chamber without putting out too much pressure so that float valve lifts off its seat. All of this equals to 1 - 5 psi. Can be adjusted by playing with pump to block gasket thickness, but you will find no difference in engine performance.
Because modern fuel injection systems are very sensitive to pressure variations, most today's mechanics blame the fuel pump first on a poor running R4 - or any other car having similar fuel system. There is little to go wrong on such a fuel pump, and is mainly a badly leaking or damaged non return valve that makes its replacement necessary.

 

[Rustyoldjcb]

A "proper" fuel pump for a carburettor is one that can fill the float chamber without putting out too much pressure so that float valve lifts off its seat. All of this equals to 1 - 5 psi. Can be adjusted by playing with pump to block gasket thickness, but you will find no difference in engine performance.
Because modern fuel injection systems are very sensitive to pressure variations, most today's mechanics blame the fuel pump first on a poor running R4 - or any other car having similar fuel system. There is little to go wrong on such a fuel pump, and is mainly a badly leaking or damaged non return valve that makes its replacement necessary.

Thanks for that. I did notice some air bubbles appearing the fuel filter, but would the NRV be the culprit? If it is delivering a good quantity of fuel maybe not? I did look at the fuel line for leaks but looks quite new. Couldn't see the connection to the fuel tank though.

 

[orsome]

There is little to go wrong on such a fuel pump, and is mainly a badly leaking or damaged non return valve that makes its replacement necessary.

Hi again, what i should do because i had to replace original petrol pump(with diaghram and i suppose including some kind of internal non return v?) with one one without any non return valve, a lot of starting problems after 1 day standing?

 

[reidalpine]

looking at you pic #2 There should be a small round filtet in there-release the two screws take off the lid and check internal filter (where you can see a stamped circle between the 2 screws) for gunk/debris,
-be careful when taking lid off as to not ruin the gasket if otherwise ok. it looks like the correct pump (Sofabex or now Valeo) to me -Reid

 

[orsome]

A "proper" fuel pump for a carburettor is one that can fill the float chamber without putting out too much pressure so that float valve lifts off its seat. All of this equals to 1 - 5 psi. Can be adjusted by playing with pump to block gasket thickness, but you will find no difference in engine performance.
Because modern fuel injection systems are very sensitive to pressure variations, most today's mechanics blame the fuel pump first on a poor running R4 - or any other car having similar fuel system. There is little to go wrong on such a fuel pump, and is mainly a badly leaking or damaged non return valve that makes its replacement necessary.

Hi, i have an diesel aggregate equipped with a Hardi fuel pump which automatically regulates the pumping amount needed. Mine has pivoted connectors.
Some say that it's better to install the pump nearby the petrol tank and not in the motor compartment due the excess heat which only makes fuekl to boil?

for english cars (like mini 848cc whichs fuel consumption should be on same level as R4 with 845cc engine?) a comparison table can be found here;

https://www.hardi-automotive.com/wp-content/uploads/Hardi-engl-Fahrzeuge.pdf

this is their most popular model:

https://www.hardi-automotive.com/wp-content/uploads/DB13312.pdf

i guess even 3psi pressure would be enough for a Zenith 28IF, but i have seen here on the forum that pressureshould be max 0.8bars and 3 psi correlates to only 0.2bars pressure

Pressure bar: 0,13-0,20/psi 1,88-2,9
Conveying capacity 60-80 l/h​

 

[ee4thkid]

I would check for vacuum leaks. Excess/extra air at idle can be a much larger percentage of the total being used by the engine. At higher rpm this percentage decreases to the point of being unnoticeable.