Losing power over 30mph.

[stu50uk]

Hi. New Member here from Aberdeenshire.

My new to me 1964 Triumph TR4 has just developed a problem when running.

Up to 30mph it is fine no problem and good pull on the engine, but over 30mph there is a loss of power and a surging with a 'chug chug chug' sound.

Sometime it dissapears and the car runs correctly again.

The only petrol I have put it it is Shell V Power E5 and the appropriate amount of Millers VSPe Power Plus.

Any pointers to what the problem is would be helpful.

[RobH]

Welcome  to the forum 'stu' -  do you have a name we can use?

Sounds like petrol starvation to me.  You probably need to start by checking there is a good supply to the pump from the tank -  its common for crud to partially block things, either the pipe or the tank outlet.  Rubber fuel pipes can collapse internally.  After-market in line fuel filters can block.

Does the glass filter bowl look clear and full?  Is the gauze clean?   

Are the carburettor float bowls clean and the needle valves clear?

Next point is the fuel pump.  Thats a bit difficult to check at 30 mph though a partial dismantlement will show the condition of the diaphragm and the non-return valves. 

[stu50uk]

3 minutes ago, RobH said:

Welcome  to the forum 'stu' -  do you have a name we can use?

Sounds like petrol starvation to me.  You probably need to start by checking there is a good supply to the pump from the tank -  its common for crud to partially block things, either the pipe or the tank outlet.  Rubber fuel pipes can collapse internally.  After-market in line fuel filters can block.

Does the glass filter bowl look clear and full?  Is the gauze clean?   

Are the carburettor float bowls clean and the needle valves clear?

Next point is the fuel pump.  Thats a bit difficult to check at 30 mph though a partial dismantlement will show the condition of the diaphragm and the non-return valves. 

Many Thanks for your reply.

Yes, Stuart is my name.

Would not fuel stavation happen at all speeds ? 

Anyway it will give me something to look at.

[Ransomes256]

Stuart,

Just had a similar fault and traced it to a sticking needle valve in the one of the SU carbs.

Replaced both with grose jets.

Neil

 

 

[Lebro]

Agree, fuel starvation. At low speed engine needs less fuel, so seems ok.

Bob

[rcreweread]

Stuart - also check the state of the inside of your fuel tank - look carefully inside and if it's rusty and flakey, then that is likely to be the start of your problem - if it's newisk or nice and clean, check their isn't some foreign debris inside which can be sucked over the tank outlet in use and could partially block the outlet.

If none of the above, check out what the others have said earlier - to test your fuel pump in it's most basic form, disconnect pipe from carbs and stick end in a jar and use the priming lever on the pump - should get a good squirt - if not, then maybe pump is defective - does it it have AC Delco on the top casting or nothing, in which case it is a repro which are not particularly reliable

Cheers Rich 

[TR4Geoff]

Hi Stuart,

Do you have SU or Stromberg Carbs? If Strombergs it might be caused by a Hole/Split in one or both of the Diaphragms.

Geoff

[stu50uk]

Thanks for your answers. I'll check out the fuel system later when I have time.

Stuart

[stuart]

You didnt by any chance drop the little foil cap off the bottle of additive in the tank did you? Or a DPO might have.

Stuart.

[stu50uk]

6 hours ago, stuart said:

You didnt by any chance drop the little foil cap off the bottle of additive in the tank did you? Or a DPO might have.

Stuart.

No I didn't drop anything inside the tank.

I actually won the TR4 in an raffle with Bridge Classic Cars. So I actually 'bought' the car for £16 (two tickets).

When it arrived the fuel gauge was low. Living in a rural part of Aberdeenshire away from E5 fuel I filled up a couple of 20 litre Jerry Cans with Shell V-Power E5 when I was next at the filling station and later filled the TR4 with a Water Fuel Seperator Filter Funnel to make sure the fuel was clean.