• Hi Guest!
    If you appreciate British Car Forum and our 25 years of supporting British car enthusiasts with technical and anicdotal information, collected from our thousands of great members, please support us with a low-cost subscription. You can become a supporting member for less than the dues of most car clubs.
    There are some perks with a member upgrade!
    **Upgrade Now**
    (PS: Subscribers don't see this gawd-aweful banner
Tips
Tips

TR5/TR250 problem getting engine running

Share this page

M

mcqin

Member
Offline
Hi Guys, quick update... I've been working on slowly restoring a TR250 that hasn't been on the road since the mid-70's. With some help from this forum I was able to get the engine running pretty well and managed to tune the engine and get the carbs synced & tuned. I have been focused the last couple months on sorting out the brakes, brake hydraulics, and clutch hydraulics. Now that I am excited to maybe move this car under it's own power for once, I start it up and I can not keep it running. Turns over and fires up, but dies immediately. I managed to keep it running for a few minutes a couple times by constantly playing with the gas and choke, but would never run well and dies right away. Seems like something simple that is not occurring to me since I haven't played with the engine in a while. Any suggestions on where I should start?

Thanks, Bob
 
I start by checking if the fuel bowls have fuel in them. A balky inlet valve can easily occur if a car sits for awhile.

If these are ZSs, removing the 'bowl' will reveal if there is fuel and something as simple as pushing up on the float may be enough to free a stuck valve if that is what you find.
 
As above, when a car sits for a long time the fuel system can get gummed up with fuel varnish. Look for any filters inline between the tank and pump. Replace any you find. If you don't find any... install a coarse element, translucent/transparent one near the pump so you can keep an eye on how it fills up. At the pump, remove the fuel fittings/line and make sure the pump inlet screen is clean and not caked up with debris. If anything got through the pump, it can/will collect in the float valves and float bowls so be sure to check them as Geo suggested.

With all that said, it sounds like you have probably installed a lot of ignition components trying to get the car back on the road. No matter how long ago you worked on the ignition, check that the points have not closed up. Reset them as necessary and make sure you put a layer of light grease on the 4-lobe dizzy cam that opens the points.
 
It's been a while since I haven't had as much time as I would like to get on this, but I have cleaned up the carbs and made sure there is no issue with fuel getting to them. I've double checked points and I'm all good there too. I still have an issue getting the engine to do more than just briefly fire up, then immediately die. I thought I would try a compression test to see if I'm dealing with a problem deeper in the engine. Since I can't get the engine to run long enough to get warm, this was done cold. Results were for 1 thru 6: 100-110-80-110-110-100. I think I have a problem, suggestions for next steps?
 
I never had problem to start my Tr4a but after sleeping 3 years on the side I was surprise that the beast won't start and later to have the same symptom as you, It was a fuel problem, coming erratically in the bowls, I had ball type valves, probably gummed. I throwed them and changed them for the classic one. No ignition cause, my ignition is electronic, no reason a composant die during the sleeping, the spark plugs won't change by himself even.
 
mcqin said:
....Results were for 1 thru 6: 100-110-80-110-110-100...
Click to expand...

The engine should run with those figures. Not ideal but may be higher after it has run a bit.

You confirmed that "there is no issue with fuel getting to [the carbs]" - have you also confirmed that the bowls have fuel in them?

Help me remember, do 250s have SUs or ZSs?
 
They came with ZS carbs.
FWIW ...Non adjustable needles, Non adjustable jets.
 
I have ZSs. I opened up the carbs and made sure the floats were moving freely and the needle valves were not clogged. I confirmed that there was adequate fuel flow by manually pumping the fuel pump with the line detached from the carbs and seeing it spurt out freely. I am assuming once the carbs are back together the bowls will have fuel. How can I check that?
 
The least 'invasive' way would be to lift the air valve so you can see the into the carb at the bridge and by using a a small tube or soda straw blow into the hole for the float chamber vent. If there is fuel in the float chamber, gas will come bubbling up from the float chamber, thru the jet and over topping the bridge as you blow.
That vent hole is the unthreaded round hole between the 10 and 11 o'clock position on the carbs'
air box mounting flange:
. 72 Carbs 002.jpg
 
So using the method suggested by poolboy, I was able to confirm that there is fuel in the bowls. Any suggestions on what to try next? I'm kinda stumped, since i already rebuilt the carbs and had it pretty running well. The few months of not starting while I worked on other things to get it rolling left me in this spot. Any additional thoughts would be appreciated..
 
I guess while the attention is on the carbs, it might be a good idea to ask if you think the carbs are flooding ?
The floats in those particular carbs don't age well and may have a tendency to loose buoyancy...the result is that too much fuel is allowed to enter the float chamber..When the chamber gets full, the excess overflows thru the jet in a similar fashion to what you saw when you blew into the float chamber vent.
Next time you get the engine running and find that it dies, immediately pull some spark plugs and look for signs of flooding, including the presence of raw gas pooled up in the throat of the carbs.
If you can eliminate the possibility of flooding, then it may be time to look to ignition related components with the adage " 90% of carb problems are ignition problems" in mind.
 
mcgin, does it start right up with starting fluid? If so you may just be looking at old gas, your car was build for 100 octane, so old 93 gas even without ethanol may be the culprit. Throw a couple of gallons of high test and some ethanol treatment in there and blow back from the filter at the pump, that will mix it up some and get the junk gas off the bottom. Spray some carb cleaner in the pipe at the carbs to blow the junk gas out of there.
Wayne
 
Define stops after starting. Does it stutter for awhile and then die? If it starts while cranking and then dies after returning the key to "run" position maybe you have an open in the resistance wire (if fitted.) It could be a loose connection in the ignition circuit. Can't remember which years but there is a start circuit to allow full voltage to the coil during starting and then puts a resistance wire in place after start up to reduce voltage to the coil to keep it from over heating.
 
skikir said:
Can't remember which years but there is a start circuit to allow full voltage to the coil during starting and then puts a resistance wire in place after start up to reduce voltage to the coil to keep it from over heating.
Click to expand...

That's a good thought. However, according to Dan Master's schematics the ballast ignition system wasn't introduced until the '73 TR6.
 
Back
Top