Hey guys.
Just got abit of an issure here that im not sure about

I have a nissan 720 with a L18 in it.
It starts and idles fine. Ive just changed plugs and leads.
But when I put my foot on the accelerator its like I hit a flat spot and it wont rev up its just wants to stall.
Im unsure of what it could be.
I was told the it could be the fuel pump not supplying enough fuel but im not sure.
So if anyone has any ideas about it, or if anyone has some information they could help me with that would be great.

Cheers guys.
Shaun.

Carby may have a blocked primary? jet?
I had an L18 do that once but it was in the idle jet and it would run but not idle. Poked a grain of sand out the jet and she was back to normal.
Could be 1 of a few things tho.
Was it ok prior to changing the plugs and leads?

It was abit worse before I did the plugs.

Is it hard to check/clean out the jet like you said?
Would carby cleaner help?

If its not that what epse would you recommend?

No its just a few bolts and screws but check as many easy things as you can prior to doing this.
Make sure you have some silicon handy if you do tho as you might break the carby gasket when you pull it off the manifold.
Some carby jets are really easy to see and get to from the lower side of the carby.
Best to remove the whole carby if you do this and do it on a clean bench where you wont drop/lose parts.


Some of the 'easy' things to check include:
Take the air cleaner off and check the carby sight glass to see if the fuel bowl float level is correct and monitor this when you try reving it.
Operate accelerator linkage by hand and check that the throttle pump on the side of the carb squirts fuel into carby throat when accelerator is operated.
Check for split/cracked and disconnected rubber vacuum hoses (to dizzy and carby etc).
Check ignition timing with a timing gun connected to lead#1.
Check points gap in dizzy, etc...

Yes, (engine off) check the accelerator pump. You should see a very strong squirt of fuel into the primary barrel when the throttle is pumped. This is for coming off idle.

If the above is ok and the peddle goes further and further to the floor but it just lacks power and won't rev pas a certain spot, then the primary barrel is likely part blocked. A hail Mary is to place rags under the front of the carb and remove the glass front. Let the gas drain. Carefully remove the float and DON'T loose that small brass sleeve on the end of the float hinge pin. It will be tight up against the front cover and will fall out.

Now get a can of spray carb cleaner, the one with the red plastic straw. In the bottom of the float chamber are two holes that feed fuel to the primary (left ) and secondary (right) jets. Direct the carb spray down into the left (primary) jet side. This will likely dislodge or dissolve any crap in there.


You probably have a can of cleaner so all that is invested in trying this is your time.

Thanks guys.
Ill give your suggestions a go amd let yous know if it makes it any better.

Cheers.

Take off air cleaner, rev it hard by hand and put your hand over the carb. This will suck your hand really hard and forces through raw fuel. Or something like that. Fixed my stanza .

_________________
1979 Datsun Stanza Coupe
1979 Datsun Stanza Coupe Project
1979 Datsun Stanza GX
1982 Datsun Stanza GX
1966 Nissan Cedric Custom Six
1972 Volkswagen Beetle
1974 Toyota Landcruiser Stallion (SWB)
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I've heard of this too. Can't hurt.... well don't look down the carb and wear ear protection in case of backfire.

If it revs fine just standing there, but hit's the flat spot when you try to drive it, it'll be a vacuum leak.
Have you checked points gap ?

_________________
Happiness is watching the race.... in your rearview mirror

So I got a fuel pump and carby off a mate of mine.
Going to install these ones on the weekend.

Ill let you guys know how I go.
Thanks for all your help.

Hey again guys.

So I managed to get the secondhand carby I got on this arvo in the pouring rain.
The ute now runs like a dream.
No flat spot. Just drives and idles perfect now.

Thanks for all your help guys.

Cheers.
Shaun.

I'm convinced the primary has dirt in it and this had to have come from somewhere. I would suggest replacing your fuel filter. Further, cut the old one open a inspect it. Has the element inside come loose? I've had that and all the crap migrated into the carb. Is it plugged? badly? What is it, sand or rust flakes? If rust, the tank and lines may be the cause. Keep an eye on the filter and change more often. Be sure to hang onto that old carb too. A good cleaning and you have a spare if this one cocks up..

Also if you put system cleaner into your fuel tank which I thought was an awesome idea to do to my stanza, it will clean out the system and all the sludge will end up in your fuel filter and possibly in your carb, this happened to me.. I did as I said above and it cleared a passage after a couple of times.
I also took the carb apart and put a kit through it as well as cleaning out the jets with an air compressor.

_________________
1979 Datsun Stanza Coupe
1979 Datsun Stanza Coupe Project
1979 Datsun Stanza GX
1982 Datsun Stanza GX
1966 Nissan Cedric Custom Six
1972 Volkswagen Beetle
1974 Toyota Landcruiser Stallion (SWB)
EziAutoParts