EFI to Carb, missing, spluttering and just not running right.

[BatmansDatsun]

Gday guys been a while since I've been on here due to work and the likes.

 

I rebuilt my l28 at Xmas time and some of you may remember I had issues with fuel and spark and the thing wouldn't fire on all 6. I managed as temp solution/test to grab a carby setup off my bro in law's c210 Skyline. I know its meant for a 2.4l and he had only ever run gas through that setup, but it starts and runs.......but not on all cyl's. I have replaced every part bar the fuel pump on this thing either from a working and running l28 or brand new part.

 

Link to the video (my apologies for any language in it)

 

I have replaced the following:

 

- Full dizzy setup

- Fuel Filter

- lines

- plugs (tried hotter and colder and different gaps on each of those)

- Leads

- FPR ( didn't make a difference so i took it off as there is a return line)

 

I have tried the following:

 

- Set timing advanced and retard on the actual spindle end

- checked valves and pistons are where they are at TDP multiple times

- Comp test all Cyls were within 10-15 psi of each other

 

I'm leaning towards the carbie setup as it is old and i couldn't justify putting a carby kit into it and re jetting it for the pure reason that i cant actually shut my bonnet with it on haha.

 

Any advice or help with this would be tops.

 

And if you are in Brisbane and have a spare carby setup (with manifold) and are willing to let me try it to see if it actually makes a difference you would be greatly appreciated and provided a carton of an alcoholic (or not) beverage

 

Cheers guys and thanks in advance

 

Nic

 

[Zedman240®]

What fuel pump are you running? EFI pumps run at 30+ PSI whereas Carby pumps run at 4-5 PSI....a slight difference...

[BatmansDatsun]

Yeh it still has the EFi pump in it, i tried to use my adjustable fuel reg to bring it down but i think it might be buggered. Would using a adjustable fuel reg be able to bring that down enough? just thinking i might buy another one this week to try it.

 

The video is up so see what you think

 

Cheers

 

nic

[Scoota G]

Sure will, about $70 on ebay.

[BatmansDatsun]

Out of curiosity what should i be looking for. what pressure should i be looking for and if you have links to one that would do the job could you post them. im looking atm but still a bit confused on them.

 

cheers

nic

[Scoota G]

Out of curiosity what should i be looking for. what pressure should i be looking for and if you have links to one that would do the job could you post them. im looking atm but still a bit confused on them.

 

cheers

nic

Any one with a gauge, i would try about 4 psi. You'll hear it when it's close to right.

 

http://www.ebay.com.au/itm/Sard-Adjustable-Fuel-Pressure-Regulator-w-Gauge-BLUE-/321128250228?pt=AU_Car_Parts_Accessories&hash=item4ac4bc3b74#ht_2531wt_1170

[Zedman240®]

With what you are running now, you have a fuel pump designed to move a large amount of fuel at high pressure through six injectors and what you need is a small pump designed to drip feed a carby. You are basically forcing large amounts of fuel through the carby and into the motor. Get a small Facet or any pump designed for carbies and replace the EFI pump and filter with one for carbies. Don't buy a fuel pressure reg for that... just replace the pump with the right one.

[BatmansDatsun]

zedman I'd love to put the right pump in there but money is the restricting factor here. The Reg would be a will that fix it sort of thing and if it does new manifold and carby  then fuel pump. So i take it you all think its overfueling then.... which is a good thing, as thats what i thought it was

 

I really appreciate the feedback will let you know how that goes.

 

Cheers

 

Nic

[Gordo]

Mate ,you need to get another pump for carbys. You will have major trouble with a 40psi pump, they are not that expensive .

[HKSZ]

You have to have the right pressure for sure, but even if you turn the pump offcarb will have enough fuel to run properly for 10sec or so.

If carb was run on LPG more than likey it needs a rebuild kit, plungers in carb dry up

[Zedman240®]

If you can get to a self serve wrecker, you can get a second hand one for next to nothing..over fueled engines don't last long.

[BatmansDatsun]

Yeh the car will not be driven on this carby setup. it was put on to see if it would fix the problem im having with fuel/the miss.

 

I would rather put the fuel pump on, but the FPR would be a way to see if the overpressure is what is causing the car to run like that. If the FPR makes it a little better (i would of bought another one anyway) then the next step is the pump. and then new manifolds and probably a twin SU setup as I could not afford triples atm.

 

Is there a specific pump i should be looking for? or will any pump designed to work on a 1-10 psi (with fpr) range be sufficient..

I really value the input here guys

 

and that carby is probably shot, i will try the local wreckers tomorrow but if anyone has one in sunnycoast to goldy that i could just swap over ( you would get it back) to see if that makes a difference, that would be amazing

[chris240]

$109......also try rocket industries or evilbay...$60-70 tops.

Simple....

http://www.weberperformance.com.au/product_info.php?cPath=59_161&products_id=31

 

If you go with SU's just stick to the trusted mechanical pump, to save $ and headache for your setup.

[HKSZ]

I think its spark, put a timing light on every lead and see if you get a constant flash

[BatmansDatsun]

Yeh spark was something i thought of, i did change dizzys and leads and plugs, and my timing light died about 10 mins after getting it to 10deg tdc @ 900RPM so it might not even be right haha.

 

get paid tonight so ill get a new timing light and call the local wreckers

 

[neRok]

According to all the info I read the other day when I went to check my fuel pumps pressure, SUs like around 3psi, whereas Holley carbs etc like around 7psi. So dont get a 'big' electric fuel pump like a Holley Red, they arent suitable.

[Six_Shooter]

Are you sure you have the correct firing order?

[BatmansDatsun]

Is it same as most straight 6's?

 

15 36 24

[Six_Shooter]

That's the firing order, but are you sure it's correct on the engine itself?

 

It's pretty easy to get a pair out of order, and it can sound much like what yours does.

[BatmansDatsun]

oh you mean on the dizzy itself? yeh that is a good point... ill go look now

[Six_Shooter]

Also make sure you have the correct reach plugs. I'm only aware of one length used on the L-series, but I have been in a situation where, the wrong reach plugs were used, and it ran rough, usually missing, and would sometimes hang the RPM. The plugs were too short in that case. It was  GM V8 engine that I had that issue with.

 

We also swapped induction systems to try to rectify the problem, but the opposite way, from carb to EFI, after trying several different carbs, since I understand EFI, well GM EFI a lot more than carb. Then we found the plug length issue.

[BatmansDatsun]

Okay so the issue i believe now is 100% the fuel pump my plugs are as black as night and as wet as well... water i spose. the plug gaps have been tried and to no avail. and the Dizzy was right. i moved them one left and one right but to no avail.

 

Fuel pump is the next step i think

 

Thanks for the help will keep you all updated.

[jamo240]

Hey Batman

 

Carbies don't REQUIRE fuel pressure as such to function (unlike fuel injection, which requires the pressure to push the fuel through the injectors as they open). With carburettors, the function of the pump is only to provide fuel to the carburettor at sufficient volume to support the flow rate at maximum power, but only at a pressure that won't overcome the needle and seat arrangement in the carburettor. The needle and seat works in conjunction with a float to maintain a constant fuel level inside the float bowl. The fuel then flows through jets and emulsion tubes at rates governed by the air flow going through the carburettor, which is in turn related to the throttle opening. If the fuel level in the float is too high, the engine will run rich. This happens if the needle and seat is defective, or if excessive fuel pressure is applied which will render the needle and seat ineffective. This will certainly be the case if you feed a carburettor with a fuel injection pump. Most carbies will not be too fussy about fuel pressure, as long as it's always there. I would go with 3-4 PSI on just about anything. If you can't afford a fuel pump to test the theory, put some fuel in a drum and hold it above the engine and simply gravity feed it to the carbie....that will enough to determine if that fixes your problem as low fuel flow rates.

 

Finally, what's wrong with using a factory mechanical pump? I have a few here, and I am sure you can get one from guys in Qld.

 

Cheers

 

Jamo

[BatmansDatsun]

Alright so I had a hunt in one of my shed's and came across a few usefull (hopefully) items.. Found a nother carby that was on my brother in laws other skyline and that one ran petrol up until about 5 years ago. I found 2 Fuel pumps both of a L24/C210 one is mechanical and the other is an electric one. I think i will just put it up for sale.. i dont expect much but hey anything is better than a car thats just taking up space.

[peter t]

Check dissy/oil pump alignment. Mine is ass about face so no one on dissy cap is not no one.