Slightly OT -- Intermittent short with my Tiger

[MadRiver]

Howdy all:

I know this is OT, but there are lots of experienced folks here, and there isn't much traffic on the Sunbeam section, so please forgive me!

I would love some help from the collective wisdom. On my way into work this morning (warm day -- into the 80s) the modern electronic fuel pump starting making an alarmingly loud clicking sound, as opposed to the normal annoying clicking sound it typically makes. I figured that the heat from the muffler was finally starting to get to the little pump. Well, as I pulled into the office garage, the engine shut off. I started it, and it idled for a bit, and then shut off again. When I turned the key again, absolutely nothing happened. No clicking from the fuel pump, no starter motor, no lights, no horn, no electrical system of any kind. I pushed the Tiger into my parking spot, and contemplated what to do next. I checked the battery connections, and they were nice and tight, and I turned the battery cut-off switch to ensure that it
was tight. All was well. Fuses were fine. Then I casually flicked on the
lights, and noticed that they were working, and then I checked all the electrics and they were suddenly working too! I tried to turn the engine over, and the fuel pump started clicking, the engine cranked a couple of times, and then everything electrical went dead again.

This puzzled me. So, I checked everything again, couldn't find anything wrong, and it all remained dead. I was puzzled, and decided to let it sit. I switched the lights on just to observe, and to my utter surprise, the lights popped on again after a few seconds. So, I turned the key again, and the whole thing repeated itself. I turned the key, the fuel pump clicked, the engine turned over, and then everything went dead. Now I'm really confused. So, I checked the battery connections again, the cut-off switch and then just let it sit. Believe it or not, the lights came back on again after a few moments. I turned the key, and then the car actually started up and ran.

I assume that the problem is an intermittant electrical short in the fuel pump brought on by the heat from my muffler. Any help from the collective would be greatly appreciated. I'm planning on driving home (no highways) once it cools a bit.

Thanks!

 

[Twosheds]

Is the fuel pump circuit fused? Typically, a short blows the fuse, but... "one never knows, do one?" As Fats Waller asks.

If you think that the fuel pump is the culprit, disconnect it and see if the rest of the electrical system works.

 

[DNK]

I agree with the good "Dr." Looks like you'll be driving the 250 for a while.

Hey doc, saw your name on the registry for Lilypons but didn't see your car. The wetness scare you away?

 

[NickMorgan]

I'm no electrical expert at all, but it sounds as though something is getting hot, expanding and breaking the circuit. Are all of the electrical items on the same fuse? Could the fuse have blown, but as it cools down the wire within is able to close the gap? When a current flows though it again it heats up and the gap opens? It certanily sounds as though the fuel pump was working hard and if it is near the muffler would probably be cavitating, then getting hotter.
I would clean up all of the connectors and replace the fuse as a starter.

 

[martx-5]

Since this is a general electrical loss, I would start at the battery again. First check what the voltage is...should be over 12 volts. Your symptoms really indicate that there are loose/dirty connections at the battery. I would remove both cables, clean the terminals up, and, at least for now eliminate that cut-off switch. After everything is clean and tight...WITHOUT the cut-off switch attached, see if that makes things work again.

Personally, I think that the cut-off switch has gotten tired, and the contacts in it are causing too much resistance in the circuit.

 

[TR3driver]

Horrible Freight sells cheap DVMs ... no LBC should be without one !

Seriously, I keep one in every car. At $5 each, it's cheap insurance. A couple of clip leads from Radio Shack are handy too.

From your description, I'd be following both battery cables back to where they attach to the rest of the electrical system, especially the ground cable. If it was a short somewhere, you'd be seeing smoke or blown fuses; it has to be an 'open', ie bad connection.

Also take the clamps off the battery and check that the inside surfaces are clean. I've seen them develop corrosion in there even when the outside looked OK.

 

[tomshobby]

Sounds like when batteries had fill caps and needed water. Possibly is a loose or corroded ground connection or ground cable.

 

[Harry_Ward]

Could be the battery recharging just enough by sittin' to get things going for a short amount of time but not getting a constant recharge from the alternator or generator to keep it going. Check the battery and the charging system first would be my guess.

 

[Twosheds]

Hey doc, saw your name on the registry for Lilypons but didn't see your car. The wetness scare you away?

Yes, I'll melt if I get wet. I just talked to a friend who had his TR8 at Lilypons. He said there were only two TR3s there. But there were three TR8s. More '8s than '3s! I guess the rain kept attendance low.

 

[RonMacPherson]

How many keys are on your key ring? If more than door, valet and ignition, remove the rest.

consistent with heat expansion, increased resistance(the sound of the pump changing) then open circuit until it cools down. My first curiousity would be to wiggle on the key when in operation, to see if anything changes. If so, this would indicate switch failing.

 

[DNK]

Re: Slightly OT -- Intermittent short with my Tige

More '8s than '3s! I guess the rain kept attendance low.

More Lotus's than anything. I guess the owners feel more confident about them starting in the rain

 

[AltaKnight]

Re: Slightly OT -- Intermittent short with my Tige

My vote is with Art that the battery is the probable culprit. They can and do go bad instantly and cause the exact symptoms you describe.
OTOH what caused the racket from the fuel pump before the car quit?
Maybe you have double trouble?

 

[myspitfire]

I owned a Tiger 260 & I remember having the same problem that was ultimatly diagnosed as an original wornout SU Electric pump.,Internal points were shot caused by inoperable heatshielding.,And if i remember right their is an internal circuit breaker that trips when theirs a problem.My suggestion would be to purchase a new pump.Cheers

 

[TR3driver]

I owned a Tiger 260 & I remember having the same problem that was ultimatly diagnosed as an original wornout SU Electric pump.

Just curious, did anyone esplain how that kept the starter motor from working ?

 

[martx-5]

I owned a Tiger 260 & I remember having the same problem that was ultimatly diagnosed as an original wornout SU Electric pump.

Just curious, did anyone esplain how that kept the starter motor from working ?

Well, the whole thing started with the original poster suggesting that he MIGHT have a problem with the fuel pump. I'm sure the fuel pump is not causing all of the other electrical losses that this car is experiencing. This reeks of a battery and/or battery cable problem.