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Lovely Run Out - But Fuel Starvation Issues :(
davidimurray - 17/5/14 at 06:01 PM

Took the car out for a run today. All was was going well until I had been sat behind a car through a few villages, got out on to one of my favourite roads, foot to the floor on a slight hill and full throttle for about 10-15 seconds to get past the car, easy off a little, round a bend then back to full throttle, noticed a little hesitation then the start of a misfire, eased off and now sounded like a machine gun, looked over at the Lambda gauge and it was just going off the scale lean. Straight off the throttle and luckily rolled to a layby a few hundred yards away. Car was popping and banging away as I pulled in, blipped the throttle and still missing so moved the car away from the road so I could whip the bonnet off. As I was moving it the misfire gradually improved until it disappeared.

As it was the first time out in any proper warmth I wondered whether the underbonnet temps were high causing fuel evaporation. Engine temp was between 85 and 95C all day. Whipped the bonnet off, everything looked ok, all leads on, crank sensor secure, carbs felt cool. Couldn't find anything so fired her backup and all seemed fine. Set off gently and carried on up the long drag up the mountain road I was on to the top with no issues. Carried on gently and all seemed fine.

Did a couple of other mountain roads fine then decided to go up one that has a very steep hill with 180degree super tight switch backs. Did the first mega steep part of the hill without any problems - I decided tto give it some beans between two of the switch backs, so coming out of one gave it full throttle in 2nd then into 3rd, breaking for next switchback, start to pull away and we have pop band bang misfire again! Lambda again on it's way to going off the scale lean. Limped to somewhere I could stop and just sat there idling and the car returned to normal now. Set off again gently and all fine. At the other end of the mountain road is a long gentle hill. Gave it some beans on the hill and noticed you could see the fuelling start to lean off on the lambda gauge.

So It looks like I have a fuel Starvation problem, either my ZX6R pump is on the way out or the fuel filters are blocked. I have noticed that the fuel pump does seem to click for a lot longer when I first turn the key in the garage.

And to top it all when I got home I found that one of my front wing stays had snapped!

Oh well, all part of the fun of these cars

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whitestu - 17/5/14 at 06:11 PM

Are you running ZX6 carbs? If so what's the set up?

What's the engine?


blakep82 - 17/5/14 at 06:14 PM

Wheres the pick up in your fuel tank? In a little sump? Just at the base of the tank? Do you have a swirl pot?
If you dont have a small sump (something like a 4" diameter cylinder, fed by a smaller hole in the tank, then consider getting one fitted


davidimurray - 17/5/14 at 06:17 PM

ZX6R carbs, ZX6R fuel pump, ZX6R filter before the pump(new 600 miles ago before the car was on the road), small plastic type filter just before the carbs in the engine bay (again new before the car was on the road).

Engine is an 1800 Pinto and was running fine two weeks ago when I was last out. Tank hasn't been run dry at all since putting the car on the road.

I'm hoping to whip the filter off the carb end tomorrow and pump fuel into a jug, then remove the filter and do the same to see if that one is a restriction.


davidimurray - 17/5/14 at 06:20 PM

quote:
Originally posted by blakep82
Wheres the pick up in your fuel tank? In a little sump? Just at the base of the tank? Do you have a swirl pot?
If you dont have a small sump (something like a 4" diameter cylinder, fed by a smaller hole in the tank, then consider getting one fitted


Tank outlet is just in the bottom of the tank, no swirl pot, but you do of course have the float bowls on the carbs as buffers. Tank had only been filled up 5 miles before so I doubt it was starvation from the tank. It also happened both times running on relatively straight roads.

[Edited on 17/5/14 by davidimurray]


gremlin1234 - 17/5/14 at 08:37 PM

quote:
Tank had only been filled up 5 miles before so I doubt it was starvation from the tank.
check the tank breather


davidimurray - 18/5/14 at 11:48 AM

Found the cause of my troubles -

http://www.locostbuilders.co.uk/forum/13/viewthread.php?tid=191370&page=1?#pid1609064

With filter fitted, took 20.2 seconds to fill a small glass, with filter removed, 7.5 seconds!

[Edited on 18/5/14 by davidimurray]