ZetecVan
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| posted on 21/6/06 at 06:01 PM |
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How on earth is my engine running?
I've got an 1800 Zetec with Jenvey throttlebodies, Bosch 803 injectors and megasquirt. Last week I had a guy round to help me tune it. I'd
just got an electronic fuel pressure gauge for the dash, and we fitted it to check the pressure. The needle only twitched. As the car ran, we
suspected the sender, and drove up and down anyway, to tune the VE bins. The numbers in the bins were very high, and we suspected a problem somewhere,
most probably the fuel pump. To eliminate the pressure sender, I got a mechanical gauge that I fitted today. The pressure is 5psi. It should be at
least 2.7 bar for the injectors I'm using.
So it looks the the ebay bought 'high pressure injection fuel pump' is actually a carb pump. But, as there's bugger all pressure in
the fuel lines for an injection system, how is it working? When I fit a correct pump, and remap the squirt, would I see any improvement in
performance/economy?
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tks
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| posted on 21/6/06 at 06:06 PM |
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yes!
more pressure is a better
spray nozzle effect??
the air would mixture easyer with the petrol.
how much bars are you of the limit??
if you increase the pressure more fuel will be injected sow you map should be adjusted down.
also make sure you measure in the injector circuit and not after the regulator.
in fact i don't know what a pressure gauge should tellyou because with the regulator it could only tell you that the pump is performing well the
pressure while useing the car is stable...
Tks
[Edited on 21/6/06 by tks]
The above comments are always meant to be from the above persons perspective.
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mark chandler
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| posted on 21/6/06 at 07:33 PM |
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You sure you are feeding fuel in the right way, ie the regulator sits on the fuel return.
Most cars will run with the fuel lines swapped as the injectors at the end of the day are just taps, if you have mapped it with low pressure they will
merely be open for longer and will more drip fuel rather than spray fuel in.
Also have you tried plucking off the vacumn tube to the regulator, with a good suck the pressure will fall to around 1bar on most cars, 2.5 bar with
this tube off.
Last resort to prove everything, get some soft grips and pinch the return hose, if the pressure remains low it sounds like a knackered fuel pump or
blocked filter.
Regards Mark
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ZetecVan
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| posted on 21/6/06 at 08:39 PM |
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Mark, the regulator is in the right place and the pipes are connected the right way. I'd guessed the injectors are dripping in the fuel, as they
are having to be held open for longer (on the map) to run.
We tried everything you suggested on Saturday. The pressure gauge barely moved when we clamped the return pipe. The fuel filter is brand new, so
I'm sure it's the pump. I'll know when my new one arrives in the next day or so.
tks - I'm hoping for better fuel economy. I'm only getting around 20 mpg, and I'm not driving it particularly hard.
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MikeRJ
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| posted on 22/6/06 at 08:43 AM |
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I can hardly belive you can get much past idle with fuel pressures that low, unless you have massive injector the engine must be running dangerously
weak at WOT.
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