over fuelling problem

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over fuelling problem

Post by lizzard_t on Fri Feb 24, 2012 6:57 pm

Hello its me , i think im going to become a pain up the rear to everyone . put the head back on my hijet 993cc efi . timing marks all correct and distributer set correctly . starts but runs like a petrol driven vibrator ! . plugs are all getting sutted up and there is strong smell of unburnt fuel from the exhaust .now ive read on here about the little box under the heandbrake all the hoses are on that . there is a electrical valve under the drivers seat with 3 pipes running from it and a blue 2 pin connector , ive unplugged that and it dose'nt make a blind bit of diference to the running .ive noticed that there is a valve on the inlet manifold with a hose comming off it , that was broken by the kind person who took the head off ,. what im grabbing at is 1) what do thease 2 items do ? and would they create an excessive over fuelling situation ? . seeing that the eletrical 1 don't seem to work . also where are the vacume pipes suppose to go from that valve cos ive got 1 left over and i can't seem to place it to anything . see i did'nt take the head off my van but its been up to me to put it back on , so when i got my van back from the v.nice person who did it , in the back it looked like a HIJET carboot sale , so im quite lucky ive got this far i suppose . .if anyone has a clue or a diagram of the vacummme layout on the 993cc engine . i would be very happy . stay happy PAUL.

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Re: over fuelling problem

Post by PFM on Fri Feb 24, 2012 7:13 pm

I can't answer your questions, and the 993 efi manual isn't much help. If you're happy with the timing, it's very likely to be incorrect re-assembly IMHO. I'd be tempted to find another 993 efi owner, maybe by posting your location on here, and do a side-by-side comparison. Comparing pics might help, but would be laborious.

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Re: over fuelling problem

Post by rich the mechanic on Fri Feb 24, 2012 7:38 pm

you should have a vacuum hose that goes to the air box under the drivers seat.
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Re: over fuelling problem

Post by HighlyJetted on Sat Feb 25, 2012 4:11 pm

Sounds like something stupid isn't quite right! Not much help I know, but well done for getting it back together so far - very tough to rebuild something you didn't strip down. I have faith that you'll get past this little hurdle too.

When you start it does it tick over? Too fast or too slow?

Is it running on all 3 cylinders? If not then the dizzy is wrong.

Make sure the map sensor is connected to the inlet manifold - that's very important.

Also can you stall it by blocking up the throttle body? If not that I would say some of the vacuum piping is letting it breath where it shouldn't.

This is proberly no help what so ever, but the 3 pot charade 993 efi's are piped up like this:-

http://dairally.net/daihard/chas/CB70Hoses/CB70_Vacuum_Diagram_translated.jpg
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over fueling problem (maybe a sticky injector)

Post by lizzard_t on Sun Feb 26, 2012 7:26 pm

A big "thankyou" for all your help ! . I think (hopefully ) that ive tracked it down ! . what i did is that i checked the timing and set it to the white dot (not the green dot) on the fly wheel (as per other posts on this fourm) . traced all breather pipes and there connection points (corrected some mistakes that i made) . and re-started the engine. still running lumpy and over fueling . so i did a HT lead test ( ie took 1 off at a time and noticed changed in engine note) . took off number 1 and engine nearly stalled . took off number 2 , and there was little/no change in engine note . took off number 3 and engine nearly stalled . so number 2 cylinder at fault . tryed new sparkplug (due to carbon fauling) no difference .So hopefully im right in thinking that it must be a sticky injector on number 2 . and not something more majorly wrong that im missing the point on . Any idears would be helpful . many thanks .PAUL.

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Re: over fuelling problem

Post by Logi on Sun Feb 26, 2012 7:31 pm

Have you done a compression test? Was the new plug sparking?
Try easy things first Smile
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Re: over fuelling problem

Post by HighlyJetted on Sun Feb 26, 2012 8:01 pm

I think you haven't got the dizzy/leads setup right.

What you can do, as i've had similar issues, to make sure you've got everything right is:-

Make your own little tdc marks on the flywheel or bottom pulley for each cylinder (as you only have one mark for pot number 1) - then get your timing light out and try it on each plug to see if its popping it at the right time.

If you put the dizzy on but 180 degrees out (not sure if its possible on your 993 but worth mentioning) , you can put the leads on so it seems write, but it'll be sparking it on the wrong stroke (eg the exhaust push) or just totally in the wrong place... three pots are a bit weird for getting your head round the stroke/fire timing Laughing give me 4 or 2 any day as i'm a bit of a stupid retard when it comes to thirds, although i do love three pots and the way they growl like half a v6.

Although they can fail, it rarely is an injector at fault, i've had loads and loads of cars brought to me that a garage has said it got a dodgy injector, but in all my time i've never had any efi petrol with a faulty injector. Lots of faulty map/tps/maf sensors and dodgy coil packs.

This is a very crude test, and i'd not recommend it although i have done it many times... if you think a pot isnt getting fuel, take the plug out - hold a blow torch near the hole - and start her up / crank it over. You'll soon know if there's fuel or not.
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Over fueling problem

Post by lizzard_t on Sun Feb 26, 2012 8:33 pm

thankyou all once again for you much needed advice . I havent done a compression test yet . That was my next plan of action just to rule out a cylinder fault . The new spark plug i put in was sparking fine , but there again so was the one that was fouled up , i read on here about the 2 marks on the fly wheel [1 green 1 white] . So i set the dizzy via the white mark . The First time i did it the van turned over but did'nt fire . So i brought the flywheel up to the white mark , took the cap off and found the arm 180 degrees away from number 1 plug . So took dizzy out re-alinged the arm and the van burst into life .the reason why im pointing towards a sticky injector is because if number 2 injector is working but not closing ,ie overfuelling then all unburnt fuel is being pushed out downstream and out . Cos the taillpipe smells really of petrol [unburnt products] . But there again thats why im a gas engineer , not a car engineer . Im probley barking up the wrong tree . Cos i don't really know what im talking about . I shall not give up , and ill do a compression test first and take it from there . Thank you once again . Paul

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Re: over fuelling problem

Post by HighlyJetted on Sun Feb 26, 2012 11:13 pm

If you get a nice long screw driver and put it on the injector, then put your ear to it, you can hear them cracking away - I would think that if the plunger/stopper/shaft thingie inside isn't moving you would get no clicking/tapping noise.
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Re: over fuelling problem

Post by rich the mechanic on Mon Feb 27, 2012 9:29 pm

I noticed when I was doing something with the plugs out that when cranked over you could see the fuel being pushed out of the plug hole on the compression stroke in order so in theory if the injector is stuck on then you should get a second puff of fuel out even if reduced as the exhaust valve is open.

The other thought is check your cam belt timing again as one tooth out retarding the cam will run but lumpy and be like over fuelling I think I may have done that one of the five times the head has been off ours.
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Re: over fuelling problem

Post by HighlyJetted on Mon Feb 27, 2012 11:40 pm

Unless the injectors are direct into the cylinder diesel style I'm not so sure about that Rich. I guess if the inlet valve is closed then the fuel would just be pooling up in the inlet manifold. Ya dig?
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Re: over fuelling problem

Post by rich the mechanic on Tue Feb 28, 2012 9:24 pm

HighlyJetted wrote:Unless the injectors are direct into the cylinder diesel style I'm not so sure about that Rich. I guess if the inlet valve is closed then the fuel would just be pooling up in the inlet manifold. Ya dig?

Good point hadn't thought of that but then I like carbs which don't waste fuel if the plugs are out as no vacuum.
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over fuelling problem

Post by lizzard_t on Wed Feb 29, 2012 5:39 pm

Hello , thank you very much for all your replys and help in my problem , its nice to know that there are people willing to help with advice , even after a hard day at work . Well i carried out a compression test and each cylinder was up to 7 bar on my gauge and all injectors are working by useing a long screwdriver i could hear heach injector "clicking", so there was no difference in pressures (esp as its number 2 cylinder thats giving the truble ) . Im going to , bring the flywheel up to the white mark (no 1 cylinder firing) take the dizzy out rotate it 1 notch on the dizzy cap so number cylinder is firing where number 2 use to fire then move the leads around on the cap to see if that makes any difference . cos at the mo number 1 is firing at appox 3 o'clock on the cap ( if thats right).

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Re: over fuelling problem

Post by HighlyJetted on Wed Feb 29, 2012 7:13 pm

Do you own a timing light?
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Over fueling problem

Post by lizzard_t on Sat Mar 03, 2012 9:29 am

Hello , yep i found an old timing light in my shead , and it still works . Am i right in thinking theres no vacumme advance on thease 993 efi ? . And you have to bridge out the diagnostic plug to get the timing mark to stand still ? . All i need to know is where abouts is the plug to bridge it out ? . Sorry for being such a pain ! . PAUL .

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Re: over fuelling problem

Post by rich the mechanic on Sat Mar 03, 2012 7:21 pm

The diagnostic plug is under the dash passenger side so stick your head in and look up slightly it is a three pin spade teminal type white plastic caseing I strobe lighted ours with out bridging it and it was a bit flickery but I time by engine speed. To time by sound/engine speed get someone to hold the throttle open slightly so you get a fast idle then adjust the dizzy back and forth untill you find the fastest speed then fix it there.
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