914 engine problems

kevster · Post by **kevster** » Mon May 08, 2006 11:56 pm

Been having an intermittent problem with my 2.0 engine. Its been serviced, new plugs, leads, rotor, cap, condenser, rebuilt 44 dellortos, tappets checked. Every now and then it runs on 3 cylinders, no. 3 being the culprit. checked for a spark ok, when I took the plug out it was blackish and wet looking, not too oily.

I drove home last night for about 1 1/2 hours and after 15 mins of being on 3 it all sorted itself out and was fine. Then for about 45 mins was happy but for the last 30 mins started to run on 3 again. Could this be a sticky valve? I thought it may be loose tappets but then it would be rough all the time? When on 3 it backfires quite a bit and sounds 'tappety' but is still driveable.

Its not pulling well when on all four as I havent checked the timing yet but im at a bit of a loss?? Seems to come and go at random.

Any ideas appreciated

rally914 · Post by **rally914** » Wed May 10, 2006 10:37 pm

Sounds like a sticky inlet valve but could be loose gide, soft spring or something stopping a good seal valve to seat, is it bad hot or cold, high or low revs, have you done comp test

rob

kevster · Post by **kevster** » Thu May 11, 2006 7:05 pm

thanks for the info rob - seems to be same cold or hot but tends to run better higher up the rev range.

I guess i can pull off the rocker cover and have a look - take off the rockers and see if anything is loose, I can also check the clearances again.

comp test is on the cards - gonna try and hire a meter.

Im wondering if a bit of gasket dropped down on to the valves when i had the manifolds/carbs off?

really dont want to do an engine drop - wnat to get some miles on for summer!!

cheers, Kevin

kevster · Post by **kevster** » Mon Jun 05, 2006 9:54 pm

done a comp test - all came up 145 - 150 so thats ok. I did notice that the no 3 downdraught is syphoning petrol into the barrel after i shut the engine down. It starts to build up above the butterfly. Could this be why i get backfiring because one cylinder is being overfed? (carbs recently rebuilt)

What would cause this?? Float level not set right or something else

davidppp · Post by **davidppp** » Mon Jun 05, 2006 10:04 pm

ello Kevster.

You are right.

The fule level is high..the needle valve may be faulty, or contain a foreign body, the pressure too high ( less than 4psi is best), or the float set wrong or even puntured..

Carb rebuilds often do more harm than good..!

Kind regards
David

kevster · Post by **kevster** » Tue Jun 06, 2006 10:50 pm

Hi David,

Ta for that - I can whip the top plates off and check the floats, also take the needle valve out and clean (I did clean them when i stripped them down but it may have got a spot of dirt in) I only set them up by turning out 1.5 turns which is the default setup so this needs to be done more precisely really.

Re pressure its just got the std pump on from the injection system. its only flooding one barrel not both which i thought was weird - wouldnt it flood both at the same time?

cheers, Kevin

Nige · Post by **Nige** » Wed Jun 07, 2006 9:20 am

The fuel injection pump will be your problem too.

Its too high pressure for the needle valves to take, surprised this hasn't happened beforehand.

I fitted a boggo standard rotary pump that fits pretty in place of the injection one when I swapped to carbs. You need 3-4 psi for carbs, even if you run a regulator with the injection pump it may still be too much pressure.

kevster · Post by **kevster** » Wed Jun 07, 2006 10:53 am

Ah great - such a wealth of knowledge around here! So that should help sort things and hopefully drop my fuel consumption!

I have a feeling that the pump doesnt switch off when its reached pressure, it seems to just either be on or off.

I'll look for a 3 -4 psi one this weekend - I seem to be slowly replacing the whole car!

Thx - Kevin

Nige · Post by **Nige** » Wed Jun 07, 2006 11:04 am

fuel pump will/should run constantly whilst the engine is running, unspent fuel would return back to the tank on an EFi setup. With carbs on a low pressure pump you don't need to do this, I just plugged up the return lines.

Surprised you haven't had fuel spilling all over the engine to be honest.

http://www.vwspeedshop.co.uk/pg/fuelsystem.htm

down the bottom part 1380 is what I have installed, think its a CB performance product. Pretty much fits where the existing efi pump fits with abit jiggery pokery.

Also if you just have the carbs on the base settings you'll probably have running issues anyway. I took mine to a local rolling road tuner specialising in old MGs and stuff, cost £50 and it ran like a different car all together, best £50 I spent on recently. Still uses too much fuel though, I'm lucky if I get 20 mpg

I haven't done the maths but it'll take £60 to fill in and it'll do about 280 miles!!

impmad2000 · Post by **impmad2000** » Wed Jun 07, 2006 1:19 pm

I have a fuel pressure regulator off a maserati Biturbo that you can try if you'd like ? It is designed to regulate the pressure at the carb (Pressureised blow through carb) to compensate for the elevated manifold pressure of the manifold.. blah blah, the upshot is that the regulator is designed to regulate pressures from 3 to 4 psi (Adjustable) but handle pressures up to 30-40 ish PSI. The spare fuel is returned to the tank as it would be in an EFI car. Because you don't need to deal with the manifold pressures, just leave off the pipe that goes to the manifold.
Sounds like it would do the job without replacing the fuel pump for now.
A loan if you want to try it out, if it works, we'll see..
Cheers
Tim

kevster · Post by **kevster** » Wed Jun 07, 2006 1:29 pm

That sounds good to me Tim - i have looked into getting just a fuel pump for £50 but also a pump + regulator for £110 (ouch).

Not sure if I need a regulator at all if the pump is the right pressure??

I could try the regulator, this does sound like a good route as any exess can be fed back, my return pipe is capped at the mo but i could re-connect.

Tim would your regulator be overkill for what I need - I will see what a reg on its own is price wise. update - can get one for about £38 but would need setting up with gauge or trial and error.

Is there a difference/advantage between a pump at right pressure vs pump + regulator?

Nige no. 3 is definitely too rich - maybe this one is suffering as it is closest to the fuel feed and is getting the overflow...

Nige · Post by **Nige** » Wed Jun 07, 2006 1:38 pm

I don't run a regulator, the rotary pump I bought is supposed to deliver a constant pressure all day long. I don't seem to have any pressure problems.

Tim's option sounds less hassle for sure.

davidppp · Post by **davidppp** » Wed Jun 07, 2006 3:19 pm

Hello again.

Simplest is best.

Buy the bog stock small Facet pump, from www.rallydesign.co.uk or similar..about 35 quid.

Fit and forget..

You must then set flaot levels etc all as set oput in the weber books..

OEM Fule injection is a million times better on the 914..try to find one if you can..

Kind regards
david

impmad2000 · Post by **impmad2000** » Wed Jun 07, 2006 4:04 pm

kevster wrote:Tim would your regulator be overkill for what I need - I will see what a reg on its own is price wise. update - can get one for about £38 but would need setting up with gauge or trial and error.

I can lend you a Gauge too if necessary ! The Maserati one is not overkill at all, fairly standard Malpassi one really, it is just that I have one lying around....
As davidppp says though, keep it simple. Or you can play around with my regulator for free (give or take the postage!)
Choice is yours mate, i'm

Tim

kevster · Post by **kevster** » Wed Jun 07, 2006 4:48 pm

ive ordered a new pump - only £27 so at least that bit is covered off. I had an old type 3 with an electric fuel pump in that packed up one night, in the pi**ing rain, in the dark, on the M25 so I dont want to go there again!!

Ta David for advice!

Thanks Tim for kind offer though