Shakedown problems

[tr7dan]

So, I managed to repair the lower front wings where I had cut away to gain access to the inner sills and have now repainted to satin black which is near to how they were when I bought the car and it's looking pretty good now - not perfect but pretty good so far.




I've covered about 15 miles so far into the shakedown period and am suffering what I think is possible fueling issues. I stripped, cleaned and re-assembled the carbs when I rebuilt the engine but only replaced gaskets and seals and have now balanced and adjusted them to the best of my abilities so am now at a process of elimination to cure the rough running and what I think feels like part fuel starvation which has suddenly manifested itself.

So far, I've checked the fuel supply up to the fuel pump and it's clean and clear with a good flow. I took the top off the fuel pump and the filter inside is pretty much spotless but as it's the original pump from when the car was built I'm wondering as to whether or not it's functioning properly. I had purchased a replacement pump a few months back but didn't get round to fitting it, but after trying to get it to fit I'm wondering if it is the correct pump ?

It will fit and bolt into position if I re-use the tufnol spacer, but it is decidedly 'clattery' when starting the engine and after a minute or less the engine cuts out, presumably when the float bowls have emptied, so I don't even know if it's pumping fuel when fited with the spacer. I don't think it's in the right position when fitted with the spacer but it won't fit without it - I can't get the bolts to locate as the operating lever fouls against the cutout in the block and holds the pump flange in the wrong position. Anybody know if this pump (top) should fit a 1980 dhc ? I've a feeling that it's maybe for an earlier car but did they even have two different pumps during the production lifespan ?

Original pump and spacer at the bottom of the pic...

[Cobber]

Life is so much easier when you bin the damned fuel pump bolts and replace them with studs and nuts.

[tr7dan]

Life is so much easier when you bin the damned fuel pump bolts and replace them with studs and nuts.

Good tip - hadn't thought of that.

Robsport are taking the pump back and sending a replacement which looks a bit more like the original....

cheers

Dan

[Hasbeen]

Beg, borrow, steel or actually buy a pressure gauge, & find out what pressure you have.

SU, & zenith carbs can not handle more than 2PSI, but need 1.7PSI to supply a 7 driven hard through the gears, so you need a low pressure gauge.

Hasbeen

[Beans]

I have the same aftermarket one (top) fitted for some years already without any problems.
Just don't use the spacer, as the lever arm will hardly reach the cam on the jack shaft.
A simple gasket will do!



And yes, soon after this picture was taken the outgoing hose developed a leak after only 4 years

[tr7dan]

I have the same aftermarket one (top) fitted for some years already without any problems.
Just don't use the spacer, as the lever arm will hardly reach the cam on the jack shaft.
A simple gasket will do!

I seemed to struggle to get it to fit without the spacer but maybe I didn't try hard enough - probably would have been easier with studs rather than bolts as suggested by Cobber. Just a thought but do you reckon it was originally designed with the tufnol spacer to prevent heat transfer from the block ?

[Beans]

... I seemed to struggle to get it to fit ...

It could be that the cam is pointing towards the pump.
This can make putting the pump in position very difficult.
Try turning the engine so the cam point away from the pump.

[Hasbeen]

The same pump was used on many cars in the era. Different engines had different spacing from the face on the block to the cam lobe. This required different lengths of the cam following arm. We had rash of broken arms or pumps here in OZ when a batch of pumps were imported with an arm too long for our & some other motors.

The answer to use these pumps was the spacer or to remove the new arm & replace it with the arm from the old pump, which was only possible with some pumps.

The fuel pressure the pump generates depends on how far the spring which pumps the petrol is compressed by the leaver, which depends on the length of arm fitted, or the thickness of spacer. This can generate pressure above the 2PSI the float valve can handle causing flooding, or pump too little causing fuel starvation. I finally went electric pump, which required a pressure regulator. The only regulators available in Oz did not supply enough fuel for a enthusiastic driven 7 when restricted to 2PSI & caused fuel starvation.

The best solution is to overhaul your old pump, & avoid all this hassle. Yes I know, overhaul kits are not available, but they are available for the early post war diesel Fordson Major tractor lift pump which just happens to be the same basic pump.

Even better if you can find one, some of the Fordson pumps include a glass filter bowl, which will help with rusty fuel tanks, & water condensed in the fuel tank, & they easily adapt to the 7.

I wish I had found this site & run a blog when I was discovering all this the hard way by trial & error.

Hasbeen

[Beans]

... I wish I had found this site & run a blog when I was discovering all this the hard way by trial & error ...

That would have given us some good reading!

[Beans]

... Even better if you can find one, some of the Fordson pumps include a glass filter bowl, which will help with rusty fuel tanks, & water condensed in the fuel tank, & they easily adapt to the 7 ...

In my case I had to fit a Filterking pressure regulator to 't Kreng, my Sprint powered TR7, to cope with the high capacity pump.
And some versions come with a filter in a glass bowl. Very convenient!
I also fitted an extra large modern inline fuel filter between the fuel tank and the (electric) fuel pump.

[tr7dan]

Also, just checking the venting of the fuel cap as that obviously could be at play here - I've had the cap to bits but I can't figure out how the venting system works, litle springs and ball bearings and stuff but, no matter - should there be a rubber washer on this fuel cap to seal between the cap and filler pipe rim and if so, are they available as a spare part ?

[Beans]

It says it is vented so there should be two holes in the ventilation plate ...
First picture shows the parts for a vented cap on top and the non vented cap below;



And in the picture below you can see a vented ventilation plate on the left and a non vented on the right:

[tr7dan]

It says it is vented so there should be two holes in the ventilation plate ...
First picture shows the parts for a vented cap on top and the non vented cap below;

Thanks Beans - so it looks like I'm missing the large rubber washer in the middle of the top pic - size I think is 2 1/2" x 1 3/8" but I seem to also have a small spring and plastic cup with a loose ball bearing in the middle which fits in one of the ventilation holes in the vent plate. No idea how it works - seems to be a one way valve set up

[Cobber]

I binned the silly locking fuel cap, the bloody thing leaked water into the tank through the lock.
I had a stainless fuelcap from a long rusted away outboard motor fuel tank laying about, I tried it on and it fitted!
It has a manual vent screw, I loosen it when I'm using the car and close it when I'm not.
It would be a pain in the arse having to do this on a daily driver, but as I only use the car occasionally... not a bother.
I think it came from a1970s Mercury outboard that had it's fuel tank rusted out, but it might've been an Evinrude or a Mariner, I don't remember.
At one time I didn't just have too many cars, I had too many boats too!

IMG_2790.jpg (75.53 KiB) Viewed 8587 times

Yes I know about the leaves, I removed the damned things after I took the pic, at least the drain holes aren't blocked, as the well hasn't got a gut full of water... It rained like all buggery yesterday!

[Beans]

... so it looks like I'm missing the large rubber washer in the middle of the top pic ...

That is the seal between filler cap and the tank's filler neck. I usually cut them from an old car inner tube

....I seem to also have a small spring and plastic cup with a loose ball bearing in the middle which fits in one of the ventilation holes in the vent plate ...

The non vented caps I have don't have this valve. And never looked in detail to the non-vented caps.