fuel pump

[micmat]

Anybody had fuel pump problems on mk2 172?

Mine can be hard to start and regularly misses at about 4500 RPM under hard acceleration,but not if you wind it up a little slower

The coil pack is ok and the fault does not come up on the readout,altho the dealer admits there is a problem (it played up beautifully when the tech drove it!)

I was wondering about a fuel problem as a possible cause.any thoughts?

 

[JAY172]

the only way you could check the fuel is by piping in an in line pressure gauge to the fuel pipe before the rail and checking the pressure.you should have a constant pressure of about 3.5bars under all rev and throttle conditions.it doesnt have a regulator dependant on manifold pressure so thats why the fuel pressure stays constantly at approx 3.5bar.ive had coil packs fault on these before which showed up no problems on clip and multimeter checks were ok even though the coil pack was faulty.same symptons as yours as well-misfire above about 3500rpm.

 

[micmat]

Thanks Jay,how do you actually check the coil pack----they dismissed it as a cause when the fault didnt read out,it sounds like you have had a very similar problem,do they just swap it and see?

 

[JAY172]

the coil pack wont nes put a fault up in the computer memory.the computer wont nes log a misfire either if its very erratic and not a complete failure on one cylinder.you can do resistance checks across the coil pack terminals but with the fault being int then that might not show anything.personally if i was doing it i would fit a coil pack and retry it.

 

[micmat]

Appreciate your help Jay, I will do that

 

[micmat]

You were right Jay,they insisted on replacing the fuel pump and putting the latest software upgrade in---result worse!!!!

They have now fitted new coil pack and assure me all is well---I pick it up tomorrow!!

 

[h3lter]

if it happens again do the check that they do!

the coil pack (if u dont know) sits above the spark plug and looks basicly like a piece of black plastic, then there should be a clip attatched to it with sum wires comin out of it!

all u do is start ure car and leave it running! and it should be struggleing if the coil pack has fd up! so startin from left dicconect the clip to the first coil pack (the clip with the wires) and the egine should start struggleing more, do this with all four untill u get to the one where there is hardly any change in the running of the car!

that normally shows which one is bost! (some times more than one can go at a time! mates misses had 2 go on her megane)

this is how the RAC etc check them any way! my mate works for rac and u learn the tricks!

 

[JAY172]

the 172 use a single coil pack not individual coils like on the other engines.

 

[micmat]

Thanks guys

Picked the car up today and she goes like a rocket!

Dealer was a little red-faced,bc I suggested the coil in the first place after our forum discussion,but they knew best!!

Anyway got a free new pump