missfiring

[daleNOVAbrennan]

Hi, i have a 1.6 8v spi fitted in a 1.0, placed my fuel pump in my engine bay for now until i get new fuel lines.Revs fine when not driving but when under load the throttle needs to be feathered other wise it miss-fires. could this have anything to do with the fuel pump position. also idles fine without the maf sensor connected but hunts when it is connected up.any ideas? fuel pump details

• 25 GPH

• 3 - 4.5 PSI
• Self Priming to 12" lift

[nova_saloon]

Leaky air hose or crap MAF sensor. or manifold gasket not sealing and can cause an issuse with the pump but i think it should be alright

[daleNOVAbrennan]

fitted a new inlet gasket today,was thinking maf sensor could funked

[Mark Sparks]

I have same problem mate also got fuel pump fitted in engine bay the HC's were of the scale but i just bought new ecu, wiring loom and air flow meter. Ill be fitting it at the weekend so will let you know if it works.

[daleNOVAbrennan]

thanks,pulls fine when ease the throttle (without maf connected) on but cant give it proper stick as it just dies.

[Lee]

These pumps are gravity fed (to an extent, they do vacuum replenish to an extent, but would struggle badly trying to do that the entire length of the car) so when you open the trottle under load, the pump cant keep up.

Move it to the back, should solve your problem.

[Adam]

What engine have you fitted?? SPi's dont have MAF sensors

[Steve0011]

What engine have you fitted?? SPi's dont have MAF sensors

i assume you have a injection pump, mount it near the tank, as said these pumps dont 'suck' very well

[daleNOVAbrennan]

sorry map sensor

[daleNOVAbrennan]

will move the pump to near the tank,but still unsure why when the map sensor is connected i hunts for revs also does this when you place finger over the pipe coming from inlet to the map(blocking off suction from inlet)

[daleNOVAbrennan]

bottom ends just started knocking now lovely,can the bearings be changed without removing the crank on this engine (1.6i 8v spi)not having much luck

[Steve0011]

YES :) you can change big end bearings, just a sump off job changing the mains.....well thats a big job, oil pump off, gearbox off and crank out :( to be honest if your doing the bearings you might as well do the lot, you will need a bottom end kit with all the oil seals etc

you have a 1.6 mpi head on a 8v spi bottom end??

i was told that the spi bottom end was'nt suited to mpi use (someone off hear as far as i can remember)

oh yes...dont do the bottom end til after you get the car running, the knock might well be due to oil pressure not getting very high as your only turning it over/running rough due to fuel starvation ;)

[daleNOVAbrennan]

no its all spi. just going to change big end bearings, clean oil pick up,new oil and filter. took spark plugs out(new last week)BLACK sooty, over fueling? will regulator make any difference,what should a 1.6 spi fuel pressure be. my pump runs at 3-4.5 psi

[MK999]

SPi should be high pressure, that's more like carb pressure afaik, but that would make it under fuel, not overfuel. Black plugs are as you say overfuelling, lean would be white, should be a sort of light to mid brown.

[Mark Sparks]

Vacume off 3.1 - 3.1 bar
Vacume on 2.3 - 2.7 bar

Auto data mate.

[MK999]

Vacume off 3.1 - 3.1 bar
Vacume on 2.3 - 2.7 bar

Auto data mate.

Which is roughly 45psi max.

[daleNOVAbrennan]

fuel pumps ****e then for a start, will a c20let pump work,or just a get a 1.2 spi tank and pump/gte tank and pump

[Steve0011]

i thought mpi was around 3 bar spi is 0.76 bar

[MK999]

i thought mpi was around 3 bar spi is 0.76 bar

0.76 bar is still higher than what his pump is providing.

[Steve0011]

but a lot less than 3 ;)

i think the guy needs to start from scratch, spi tank and pump a work from there. do you agree? :)

[MK999]

but a lot less than 3 ;)

i think the guy needs to start from scratch, spi tank and pump a work from there. do you agree? :)

That's his first move, but it is likely to make his problem worse as it's overfuelling currently, unless it's the ecu trying to stick the injectors wide open to get the lambda correct because it finds it's lean at WOT or something similarly funky.

[Steve0011]

just had an idea.... some time ago i had a 1.4 spi the emmisions on MOT were way too high, need to be 0.3 or something like that, it was actually 24 like tha car was on permanent choke tuned out to be the water temp sensor, a 90p fix.

i long for the days when things were simple, fuel, carb, spark and go :)

[daleNOVAbrennan]

wish i kept with a carb now,what would it take to put a carb on this engine,its a coil pack type would it be as simple as just disconnecting the injector and fitting a carb (im assuming its not that easy)or a different head,manifolds,carb,dizzy,coil.

[Steve0011]

your loom will be all wrong for carb, best trying to stick with it. you say your pump runs at 3 to 4.5 bar? this is way too high it should be 0.76 for a single point injection. 3 bar is for multi point

take no notice of revious post saying 3 bar is carb pressure ITS NOT. carb pumps deliver at 0.19 to 0.25 bar

change your pump and work from there :)

[Steve0011]

if your stuck, i have a single point 'in tank' pump, you can have it if yours is an in tank setup

[daleNOVAbrennan]

its 3 to 4.5 psi which works out to about 0.27 bar i thinks, all the wiring off the 1.0 carb engine is still there, just hidden away.still using the carb tank with a return brazzed on,thanks for the offer though.

[daleNOVAbrennan]

to be honest thinking about, rebuilding the 1l of pure power and fitting that back in its starting to piss me off now lol

[Jon_nova1]

dude your in widnes! what you upto saturday?;)

[daleNOVAbrennan]

probably working,but if not will be trying to sort this ******* out lol

[Steve0011]

just looked back and your post has been edited, did you change bar to psi? :D if not i got confused by the 'auto data' posts giving bar pressures

anyway sounds like you have the correct pump, its such a shame i threw out an inlet manifold and the spi just a couple of months ago you could have tried that

have you run the car without the air filter? is the air filter clean?

go see if you can find an injector a your local scrap yard, they are quite expensive new

[Jon_nova1]

If your not give me a pm before the weekend and we'll nosy on down:thumb:

[daleNOVAbrennan]

i mite go and see what i can rape there's a few novas in scrap yards round this area

[Steve0011]

if all fails, you could surf around and pick up a GTE engine, box, loom and tank/pump for about £150 -£200 me thinks :)

[daleNOVAbrennan]

that sounds like a back up plan if all else fails

[Steve0011]

i mite go and see what i can rape there's a few novas in scrap yards round this area

dont forget to look at the astra's as some had the same engines :thumb: different looms but the engine layout is the same

[daleNOVAbrennan]

will let you know if im working jon nice 1,will look at the astras too