[worldo]

been having fuel issues on the last 4 or 5 times out wheeling. Everytime i am climbing hills for too long my car dies like it has run out of fuel.

i did search this problem but no one really gave an answer to solve the problem.

a fix for this problem would be sweet.

cheers

Ricky.

[Gwagensteve]

It's not going to be possible to provide an "answer" only things you can check.

#1 - the fuel pump. It's likely to be getting lazy by now. A worn pump will fuel the car on flat ground fine, but on a steep hill it can't pull the fuel up from the tank when it's much lower than the fuel pump. These pumps are getting quite old now. I've seen a few cars with unresolvable, seemingly random fuelling issues fixed with a new pump. Mine was one of them when I was still running a carby 1.0 litre.

Bear in mind Suzuki genuine pumps are upwards of $130. Generic pumps are much cheaper but are apparently rubbish (and that's from someone who used to sell them)

Do you have any crimps/dents in the fuel line from the tank to the pump?

Is the fuel filter in good nick?

Is the tank clean? I've seen cars with lots of little "marbles" of debris/fuel tank putty etc in the bottom of the tank. These could be restricting supply.

Are all the hose clamps/rubber hose in the fuel system in good condition and tight? A loose hose clamp might pass air under vacuum and prevent fuel flow, even if it's not really leaking when stationary.

Have you had water in the fuel? It might be possible you have ended up with water in the float bowls and on angles you're getting some water through. (?)

Steve.

[worldo]

written down every thing you have sugested and will check each through the week and replace filter.
cheers for suggestions.

[missmyljdaze]

fuel level in the carby bowl too low?
Depending on the angle or gradient you are driving, it can alter the fuel level in the bowl depending on where the float pivots from.
Old school fixes were increasing the fuel bowl capacity by modifying the bowl, or mounting the carb on an angle- but angled mounting can affect the carb when driving on different slopes.

You are probably draining the carb faster than it can be filled- due to the angle causing a lower level in the bowl resulting in less fuel, contributing factors could also be a blocked fuel filter, dodgy fuel pump or crushed fuel line restricting fuel feed?

What have you tried already?

stephen.

[alien]

if its the standard carby the angles shouldnt be an issue... the stock ones are quite well designed for that sort of thing. webers on the other hand....

[worldo]

only thing i tried was going out with more fuel in and didnt seem to help. and i havent been planning on going out just ending up wheeling somewhere so around town i dont have the problem and forget ahaha.

its a standard carby.

i will be checking all fuel lines this week and changing filter and then continue down the list until i figure it out.

[Gwagensteve]

It's seems like there's been a change fairly recently, so I disregarded the obvious shortcomings of a carb in general.

Had the OP mentioned "my car bogs and dies on big compound angles and won't restart until its sitting almost flat" or "my car dies three or four seconds after a bounce when climbing" I would have said it's just a generic carby problem and nothing can really be done to eliminate it.

wordlo - 99% it's the fuel pump.

Steve.

[worldo]

yeah ran sweet with no problems until about 2 months ago.

i will still check everything that has been suggested just to make sure its all good aswell.
thanks steve

[want33s]

Sounds like the fuel pump to me too.

[SuziBlu]

IF its the fuel pump, wouldn't it do it regardless of the angle.

I offer no suggestions at to the possible cause, but can't see it being a fuel pump issue.

[Gwagensteve]

SuziBlu wrote:

IF its the fuel pump, wouldn't it do it regardless of the angle.

I offer no suggestions at to the possible cause, but can't see it being a fuel pump issue.

Nope. no way. Seen it too many times.

Car runs fine on then flat, but on a steep angle the pump can't lift the fuel out of the tank - it's too hard to draw.

On flat ground the tank is maybe 500mm below the pump. On a hill it could easily be three times that. That's a lot harder for the pump to draw, and a worn pump can't manage it.

Steve.

[SuziBlu]

Steve, I trust your knowledge, but, lift is only 0.5psi per foot of height, so, a pump that can push fuel thru small apertures, small lines, fuel filter etc, and deliver 3psi for running, constant, should really not be bothered with a lift as described.

The 500ml below the pump I agree with, 3 times that, crikey, vertical wall ?? On a short WB like a sierra, unless totally vertical I cannot see the 1.5m lift

Also very mute point, the pump does not draw, it delivers.

Some pumps are suction, some are delivery, some are both, but not many.

Again, cannot help, but trying to learn and also offer my meager knowledge.

[SuziBlu]

Actually I lie, lift is 0.5psi for water, for fuel it is ~0.4PSI

[christover1]

Old fuel pumps crap the diaphragm, bits of which stuff up the carby.
A fuel filter between pump and carb is wise,
as well as gwagens suggestions.

[Gwagensteve]

Here we go... again.

The theory:

A) A fuel pump in a sierra has to lift the fuel out of the tank- true or false = True.
B) The further above the tank the pump is, the harder it is to lift the fuel out of the tank= True
C) Changes in head pressure will result in changes in delivery pressure is the pump is at maximum flow= True
D) Fuel pumps contain moving parts which wear and therefore become less effective with age= True

Have I missed something?

My experience:

On my car, and others in our club, we experienced poor performance on steep hills. With no other changes except replacing the fuel pump for a new or known good pump, the problem disappeared.

Suziblu, you've asserted that you cannot help, but I am helping from my personal experience.

It surprises me you doubt this - your figures prove it's real. If the pump delivers acceptable flow against (let's say) 500mm of lift, what effect on delivery will doubling this lift have? It can't be none. It might be very small, but we're only talking about 3PSI of delivery here.

Steve.

[SuziBlu]

yea ok steve, i will go sit quietly in the corner as per your demand.

[twitchy]

Gwagensteve wrote:

SuziBlu wrote:

IF its the fuel pump, wouldn't it do it regardless of the angle.

I offer no suggestions at to the possible cause, but can't see it being a fuel pump issue.

Nope. no way. Seen it too many times.

Car runs fine on then flat, but on a steep angle the pump can't lift the fuel out of the tank - it's too hard to draw.

On flat ground the tank is maybe 500mm below the pump. On a hill it could easily be three times that. That's a lot harder for the pump to draw, and a worn pump can't manage it.

Steve.

gotta agree with you here champ +1!

[want33s]

SuziBlu wrote:

Also very mute point, the pump does not draw, it delivers.

Most mechanical pumps work by moving a diaphragm against two opposite valves. 1 inlet 1 outlet.
Fuel is lifted from the tank and through the pipes to the pump by the vacuum created in the pump.
Fuel is pushed towards the carby by compression pressure between the diaphragm and valves.
Fuel pumps pump a lot better than they suck especially when old.

[Gwagensteve]

From a brief glance at the cross section drawing in the FSM that's the arrangement of the Sierra pump.

It's not impossible to imagine that their ability to lift is the first thing to go.

Steve.

[stockman]

My experience with the mechanical pumps is that they get worse over time rather than just die.
I have seen symptoms described by the OP, and I have seen a Sierra that would idle all day long and free rev but under load would die after 30 seconds (even on flat road).

An easy way to diagnose it is the fuel pump would be to add an fuel filter between the pump and the carby. When it starts to die put it into neutral and let it idle. Quickly pop the bonnet and check the filter, if the pumps gone you should see air bubbles come through the filter.