View Full Version : TR4/4A TR4 mistery engine problem - any ideas

07-16-2009, 10:03 PM
I was driving my TR4A today and it just stopped running. I was only a mile from home so I called the better half to come with tools.

A quick look in the carb bowls showed that bothe were dry, so I used the pump lever (the pump is a new one from Moss about 300 miles ago) on the mechanical pump and nothing came out of the bowl covers. So, I head home in the family car to get my spare pump, leaving my wife to sit with the car (it was a no parking zone so I figured she could talk here way out of a ticket) and the carb bowl covers off and just laying on the bowls (I did not tell my wife the carbs were apart - mia culpa). While I was loading the new pump and more tools in the car my cell phone rings and my wife tells me the car is idling just fine should she drive it home. I told he t turn it off, fearing fuel pouring onto the manifold.

When I got there the bowls were full, I installed the covers and drove it home. I seemed to run just fine.

This is a recent frame off car with a rebuilt engine and as I said, an even newer pump.

Anyone have any idea what happened?

Sorry for the long post.

07-16-2009, 10:37 PM
First guess, did you get a new gas tank? old tanks will tend to have rust and crud in them, as you drive the car it will clog as the fuel pressure builds through a tight point, then when the pressure goes away car runs fine until it happens again, look for sediment in the bottom of the float bowls, blackish to brownish reddish looking usually.

Solution is new tank or clean out tank and use a tank sealing kit, and usually add a fuel filter for good measure.

Good luck and have fun with the TR4

07-17-2009, 08:00 AM
I agree with glemon but also is the tank vented correctly.

07-17-2009, 09:28 AM
thanks for the ideas, I will check the bowls for sediment and to see if it is vented (though I don't remember a vent in the TR4 like the TR3 has, but when it was not starting I did open the tank cap and try to start it). It was not a new tank but it seemed in good shape when I looked inside. The tank had been stored inside with no fuel in it for at least ten years when I got it, but it did have two pin holes in it, which I soldered shut.

Don Elliott
07-17-2009, 09:40 AM
How old are the rubber hoses between the fuel pump and the carbs ? I suspect that the ethanol is swelling the insides and blocking the fuel flow. I had this about 10 times during 2007. I took the pump outlet pipe apart and had fuel flow. But none was pumping out the line up top. Also the float bowls were empty. After a while it would run again. Couldn't figure out why. It was Randall you wrote about the old rubber hoses.

I now add 4 oz of Marvel Mystery oil to each fill-up and I changed the feed hose on my early 1958 TR3A. I had a new hose made by a local hydraulic shop and have had no problems since. But I buy gas at Shell or ESSO - never again at Sunoco or Petro-Can. Where did you get your last tankful ? And I haven't been back to the USA since.

See my new hose at the lower right feeding the banjo fitting into the float bowl for Carb #1 and then contiuing to Carb #2 under the filter for Carb #1.

07-17-2009, 11:07 AM

This happened on my TR4 and the only piece of rubber hose in that car's fuel system is a 3 inch length just before the fuel pump (I was worried about a hard line all the way to the engine in case the engine movement would be a problem). Other then that there are the little connectors at the carbs themselves but the hard line touched the carb input there. The rubber is four years old (which is when I finished the the TR4 restoration).

I like your fuel lines on the TR3 though. I might get some made for mine since it is apart. Did you supply him with the banjo fittings or was he able to source them?

My last fill up on the TR4 before this happened was two or three days before and it was from Shell. I have been using shell of esso ever since you told me about the ethanol problem (and I had my fuel pump rebuild kits fail repetedly).

07-17-2009, 11:47 AM
I would suspect that when you fiddled with the fuel pump, something happened. she obviously tried to start the car and it did, so the pump was working again. Could be the pump, could be dirt from the fuel tank. that would be my guess.

07-17-2009, 12:06 PM
thanks for the ideas, I will check the bowls for sediment and to see if it is vented (though I don't remember a vent in the TR4 like the TR3 has,I'm not certain, but I think if you look at the gas cap itself, there is a small hole in the spring-loaded metal plate that actually closes off the opening to the tank (underneath the chrome outer cap). That's the tank vent.

07-17-2009, 02:14 PM
When that happened on my 4A back in '82, it turned out to be rust from the tank. The rust accumulates in the fuel line or fuel filter until it plugs. Then, after there is no pressure from the fuel pump, it relaxes and lets fuel flow through for a little while. If that is the cause, you will be able to travel shorter and shorter distances. I installed an inline fuel filter back then, and went through two or three until I finally took the tank out and fixed the problem by having it tanked and coated. I remember coasting to the side of the road, pulling out a screwdriver and taking the fuel line loose under the rear wheelwell and blowing on the hose until I heard it bubble in the tank. Of course then I got a nice mouthful of gas!

My daughter had a midget that did the same thing about 20 years later. Her solution was to sell the car.

07-17-2009, 02:32 PM
Looks like dirt is the majority answer. I just wonder how it blocked both bowls from getting gas.

On the subject of the vent hole Randall, you are correct (as always) there is a little hole in the cap as you described. Foes this mean for my TR3A I can drill a similar sized hole and then plug the larger vent line that is in the TR3A tank. My goal with the TR3A is to not smell petrol in the garage for the first 24 or 36 hours after I park it. Though I suspect the rebuild carbs will go a long way in that regard (those old cork seals were hard as a rock and I replaced them with the modern viton(?) ones).

07-17-2009, 04:08 PM
Foes this mean for my TR3A I can drill a similar sized hole and then plug the larger vent line that is in the TR3A tank. Check your cap first; mine have all had the hole. I plugged the vent line many years ago, because I found that with a nearly full tank, it was slopping fuel on the ground in hard turns.

Which reminds me, I still need to do that on the project TR3.

The danger would be if you (or someone) were to fill the tank full to the brim; then the fuel might warm up and expand enough to come out the cap vent and spoil your paint. I just make it a point to never fill that full; but once upon a time I had a gas station attendant try to do it. That was before I plugged the vent line, and I had to yell at him before he noticed that he (and the car) were in the middle of a spreading pool of fuel.

And before anyone comments, I believe it's still the law in Oregon that the station attendant must pump your gas. At least it was the last time I was in OR.

07-17-2009, 04:11 PM
That is nice to know. Did you plug it at the tank or at the end of the vent line. I guess a fine thread bolt with the appropriate washer would do it at the tank. Maybe a brass bolt so as to not make a spark if it were to be removed??

BTW I did check the TR3A cap and it did not have a vent hole, while the TR4A did have a vent hole.

07-17-2009, 04:19 PM
I just put a solid bolt through the vent's banjo fitting. That stopped it up nicely.

07-17-2009, 05:58 PM
Bolt should work fine, but I went the other way. Seemed easier at the time, don't recall why. Maybe it was because I already had the car up on jacks.

07-17-2009, 06:14 PM
If you had some pinholes in the tank the "the fuel line is clogged with crud" answer is even more likely. But yes it could be venting or the pump as well.

Good luck