406 wont rev - starts cleanly then no throttle

dfoss · Unread post by **dfoss** » 28 May 2008, 16:32

My 1996 2.0l 406GLX starts ok but as soon as you try to rev it it drops to a sort of hunting tickover - about 800 revs - I managed to roll it home on tickover but it wont rev. (nowhere near a 3000rpm limp-home state).

Edit - Now it's cold it starts but can't maintain a tickover

All warning lights go out but the service light symbol will re-appear when it gets very slow.

It may be co-incidence but at the same time the odometer display disappeared, it returned since but the fault is unchanged - that's happened before but without any other faults.

After a short time - like 15 minutes - when I switch on the ignition the fuel pump will buzz about 2 seconds then stop - and if I stall it or switch off and then start again I don't get that 2 second burst again on the pump - does that mean it's pressurized the fuel line OK?

What can I check? I have wiggled all the connectors I can see.

Edit - now the missus tells me that over the half mile before it lost power on her the speedo was playing up although the revcounter appeared to be OK?????

AndersDK · Unread post by **AndersDK** » 28 May 2008, 19:38

Try the fuel feed hose to the injector system. This will instantly reveal if there is a fuel blockage or the pump is weak :
unplug the fuel feed hose and lead into a jar or empty bottle.
Do a couple of ignition on/off cycles listening for the pump buzzing.

Each time the pump charges for its 1.5-2 seconds running, it should easily deliver something like 50-100mL into your container.
Have your missus do a cycle while you watch the feed hose spurting into the container to further get an idea on the function. The fuel should literally spurt/jet out the hose from a healthy working pump.

dfoss · Unread post by **dfoss** » 28 May 2008, 19:57

Thanks anders - I'll try that
'k - I have jubilee clips on the right hand (veiwed from the front) of the two rubber hoses that goes from the fuel rail back to the tank - I don't know whether thats flow or return - but with the top clip slackened so that I can pop out the white plastic 90 degree fitting - when I turn on the ignition and crank it I only get a dribble - from the tank side - and she does not fire up at all.
re-connect and after a few goes back to clean start then dies.

So is that conclusive? is the pump fulty? - or does it just tell me that the pump has failed safe in a leak situation?

AndersDK · Unread post by **AndersDK** » 28 May 2008, 21:46

You may say that a safety pressure sensor would be logic, to disrupt the pump if the pressure wont build up.
But thats not the case here.

The studs on the throttle housing should have arrows indicating flow of fuel.
If you then positively have no feed of fuel, you then have either a blockage or a defective pump/wiring.

If you can locate the feed wiring to the tank/pump, its rather easy looping the pump to a live +12V feed positively checking it out. Its always nice having a conclusive answer, before forking out the £50 or more-ish for a new pump.

dfoss · Unread post by **dfoss** » 28 May 2008, 21:59

Your talking my language Anders - I'll hook that up in the morning and check it out - I'll keep you posted - thanks

dfoss
When you get to my age every day is a new experience

dfoss · Unread post by **dfoss** » 29 May 2008, 13:37

Result

First thing this morning I put 12v on the pump itself - it ran but only delivered a dribble at the fuel rail. Went and got a new filter - fitted it - left off the fuel feed to the rail at the white connector - confirmed that I had volts at the pump's plug on switchon and cranking - then plugged it on and let it pump fuel up through the line and down a tube into a jar - no problem.

Tightened up the fuel pipe to the rail and

bingo - five times round the block to get up to normal temperature - no problems.

So why did it happen? I cut open the old filter and saw that there is a long can glued to the middle of the coil of filter paper and it had come unglued and could piston down to the end of the can and neatly shut off the fuel. The filter had been put on backwards. At the other end there is a plastic "grating" for want of a better word - that ensures this does not happen -also supporting the end of the roll of filter paper.

It was me that fitted it two years ago

My only defence being I had carefully put it on the same as the one I took off (and the rubber cap that protects it seemed to fit the welded end more snugly)
-completely missing the small arrow, which immediately rubs off in petrol covered hands.

So there we go - a cautionary tale - many thanks to those who replied.

AndersDK · Unread post by **AndersDK** » 29 May 2008, 16:09