Dax Rush V8 Help Appreciated

Dax Rush V8 Help Appreciated

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Banjo Man

Original Poster:

16 posts

81 months

Friday 6th November 2020
quotequote all
Hi Guys

I'm wondering if anybody could perhaps help with a problem with my Dax Rush V8 which is peeving me. Greatly. It has a Rover V8 with Mallory electronic ignition. The coil is brand new. It has an edelbrock 4 barrel carb and a Malpassi fuel filter (brand new) and electric fuel pumps which is working well.

The car starts very well first time. No blips or odd noises and runs perfectly for 20 mins in all gears, fast and slow in all tempretures. Then after about 20 mins of running it just peters out, normally at a junction, but it can easily just peter out at 60mph. It wont bump start again if I try that. The carb is full of fuel and jets working. When I try and re-start it it just turns over and over with not much sign of anything in the way of life.

Can anybody suggest anything that might be causing this problem? Any help or pointers would be much appreciated. It's not fuel evaporation. The rotar arm looks in good nick as does the inside of the distributor cap. After that its all very electrical and beyond me. I've just pushed the car a mile and I'm knackered and in need of any assistance you can give. If I try and start the car in an hour or two it will start, easily. You can sense my frustration.

Thank you for any assistance

Andy

sideways sid

1,165 posts

176 months

Friday 6th November 2020
quotequote all
Fuel freezing in the carb?

Banjo Man

Original Poster:

16 posts

81 months

Friday 6th November 2020
quotequote all

Thanks for getting back to me. The car did konk out today and it is very chilly but it does the same on warmer days too. I have had a look down the barrels of each carb and there is fuel to be seen. A mystery.

smokey mow

277 posts

161 months

Friday 6th November 2020
quotequote all
I’ve seen similar symptoms with a blocked fuel tank breather. Is there a hiss sound when you remove the filler cap after it’s been running for a while?

Banjo Man

Original Poster:

16 posts

81 months

Friday 6th November 2020
quotequote all
To be honest I haven’t checked but it doesn’t run long enough really, but I will
Check if I can get it going tomorrow. Thanks very much for the assistance.

Steve_D

13,181 posts

219 months

Friday 6th November 2020
quotequote all
You mention plenty about fuel but I don't see anything about confirming you actually have a spark.
Do you?

Steve

Frankthered

1,432 posts

141 months

Friday 6th November 2020
quotequote all
Old Skool (amateur) mechanic advice would be that the most likely issue would be the ignition system.

Are there sensors on the distributor and elsewhere on the ignition system - in the early 90s problems like you describe would be sown to a sensor failure (diodes or transistors breaking down in the sensor I believe). I had a similar problem on a Fiat Uno (I know) which first appeared when everything got hot when sitting in traffic, but got worse to the point where it would cut out just driving along. Give it half an hour (or so) and it would go again for another 20 minutes.

Might be worth your while talking to somebody with the right sort of diagnostic kit.

If it does turn out to be fuel related, could it be over-fueling - is there a smell of fuel when the car stops?

Happy Jim

796 posts

200 months

Friday 6th November 2020
quotequote all
smokey mow said:
I’ve seen similar symptoms with a blocked fuel tank breather. Is there a hiss sound when you remove the filler cap after it’s been running for a while?
This would be my first port of call as well.

Jim

Banjo Man

Original Poster:

16 posts

81 months

Saturday 7th November 2020
quotequote all
Many thanks for all of the advice, it's surely is appreciated.

Steve - As the car was running so well when it did run I thought the ignition system was probably okay, however it will not re-start which is actually a good thing as at elast there is something to hunt down, rather than an intermittent fault (total nightmare) - well it turns out there is no spark in its current state of not starting. Switched over the coil HT lead for a new one and no difference. Ballast resistor is about right at 1.5 oms. Sort of leaves the Mallory distributor. There just isn't anything left to check really as its all quite basic.

I don't think its over-fueling as there is no smell when I switch off the engine (when it did run).

So, that's where I am.

Thanks again guys for the hints and tips.

Belle427

5,031 posts

194 months

Sunday 8th November 2020
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Check for a good fat spark at the king lead, may narrow it down a bit further.
The distributors are pretty reliable, is it the type with the separate electronic box?
Some pictures would help.

Happy Jim

796 posts

200 months

Sunday 8th November 2020
quotequote all
Banjo Man said:
Many thanks for all of the advice, it's surely is appreciated.

Steve - As the car was running so well when it did run I thought the ignition system was probably okay, however it will not re-start which is actually a good thing as at elast there is something to hunt down, rather than an intermittent fault (total nightmare) - well it turns out there is no spark in its current state of not starting. Switched over the coil HT lead for a new one and no difference. Ballast resistor is about right at 1.5 oms. Sort of leaves the Mallory distributor. There just isn't anything left to check really as its all quite basic.

I don't think its over-fueling as there is no smell when I switch off the engine (when it did run).

So, that's where I am.

Thanks again guys for the hints and tips.
I had a Mallory dual point dizzy that crapped out on me with no spark, the condenser connecting bolt had twisted internally and was shorting out (easy to spot with the cap off).

Regards

Jim

tonycordon

244 posts

191 months

Monday 9th November 2020
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I had a similar problem some years age with a Kawasaki ZXR750 H1 'bike. It would start and run perfectly for about 20/30 minutes, but would then peter out and refuse to restart, I tried 'everything' to no avail, until I replaced the electronic ignition box. Hey presto never had the problem again. I guess the electronics failed as they 'warmed up'!

Caddyshack

2,831 posts

167 months

Monday 9th November 2020
quotequote all
I would get it to someone like Dave walker at emerald and get it run up on the dyno and get them to do a full diagnostic and set up. It will run better, make more power and they should solve the problem. Make sure they know in advance what outcome you need.

Banjo Man

Original Poster:

16 posts

81 months

Tuesday 10th November 2020
quotequote all

Thanks again for the support. I'm pretty sure its ignition related. My distributor is a Mallory Type 47 breaker-less type (electronic ignition), so other than changing the rotar arm and cap there isn't too much more i can do with my slightly limited knowledge. I have ordered new ones just in case.

The replies re the Fiat and Kawasaki sound very familiar.Thanks, usefulto know.

I can adjust the amount of fuel that gets to the carb as I have a Malpassi fuel filter (currently set at about 3 psi on the gauge) - this unit has also been over-hauled. I think 3 psi is about right for a Rover V8, but if its not please do let me know. Plenty of fuel gets to the carbs.

Thanks again everybody, really appreciated.