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TR7 Ignition solutions

To: TR8@mercury.lcs.mit.edu
Subject: TR7 Ignition solutions
From: gall@beta.uleth.ca (Greg Gall)
Date: Wed, 6 Jul 94 17:35:16 MDT
I think I can safely say that ny TR7 is running properly (knock on
wood!). Thoe who were following my plight may remember that the car
would idle fairly well, and then sputter and die when driven around the
block (10-15 min. after starting the car). To fix the problem I did the
following:

Using a timing light, I noticed that the car was not firing at higher
RPMs (4500 plus).

- I inspected the plug wires (they had always arched a lot) } 2 bad, one
completely open, other reading 50K Ohms (instead of proper 20K Ohms).
Replaced with a spare set (from a Celica).

[problem persisted]

- Inspected the distributor } shaft worn - wobbles about 1mm. Replaced
ignition system with Delco all-electronic igniton (from 80/81 TR7) -
took 1/2 day to locate correct wiring harness (found in Spitfire),
crimped on terminals, made custom mounting bracket for coil/amplifier.

[problem persisted, although now idle is smoother]

Timing light check now ok., suspect stalling to be fuel related.

- Noticed that car has incorrect (?) petrol pump. Spent 1/2 day trying
to sort out what goes with what of the 3 pumps I have. Notice that no
matter how I affix it (spacer or not), Canadian Tire pump is plain
WRONG! Curse at the idiots who supplied the thing. Finally install the
oldest pump - without the spacer.

[problem persisted]

- Noticed that car consistently backfired through one carb. Pulled
damper } needle completely gummed up. Cleaned carb, polished needle with
SOS pad, reassembled.

- Repeated procedure for other carb, although it appeared fine.

[problem persisted, although car now idles VERY RICH rather than VERY
LEAN (as before)]

- Suspect bad floats, rear carb occasionally floods, spilling gas out
the vent tube. Removed float chamber from both cars } one float valve
sticks shut. Replaced with valve from parts carb.

[problem persisted - I didn't expect this last procedure to help it]

- Noticed that little petrol leaks from tank line when disconnected from
carb. Trying to blow into tank reveals a patially plugged line. After
emptying 4 spare tires into line, petrol line still restricted. Problem
found to be inside tank. After unsuccessfully trying to push a wire
through the tube, I determined that the tank sender/feed line would have
to be removed. After unsuccesfully trying to syphon the petrol from the
filler, I opted for the deluge technique (10l into a bucket, 2l onto me
8^) ). Found rust scale on EVERYTHING inside of tank (guess I shouldn't
have parked it for 4.5 years 8^) ). Cleaned feeder tube, slit fibre
filtre found on end (seemed to be plugged with fine particles). Spliced
a filtre between tank and line running to engine compartmanet (this will
catch those 'lil rust devils 8^) ).

[problem gone! - at least until 1/2 hour later. Car stalls and stops]

- Notice that "low fuel" light is on, while gas gauge is on
empty...Hmmm, wonder if I ran out of petrol? Returned with jerry can,
pulling line from pump reveals that car IS out of petrol, line still is
clear of obstructions. Dumped petrol into car, started after getting
fuel to carbs.

[Wow, what a concept! Working light and gauge...hasn't worked in years!]
8^) 8^)

- Made one very poor attempt at setting the carb mixture } screws did
nothing. Took to local Triumph mechanic, 10 min later (with special tool
in hand), he got the car to purrrrr! 8^) 8^) Left the place short $10 }
well worth the money!!!

------
Final solution:

Tank partially plugged with rust scale. Modification of tank filtre,
along with, addition of new external filtre solved problem.

Car now runs beautifully... After 4.5 years, I am now enjoying top down
cruising again. 8^) 8^) 8^) ... forgot how great it felt!

Once again I'm goin' topless!

Greg.
-- 
Internet: gall@ultrix.uleth.ca

"You miss too much these days if you stop to think"
By a famous Irish poet and philosopher, Bono of the band U2, circa '91.

'76 Triumph TR7 V8 (Buick 350) Fixedhead Coupe.
'77 Triumph TR7 4spd, A/C Fixedhead Coupe.              _   /|  A
'79 Triumph TR7 Auto Drophead Coupe. (VROOOM!)          \`o_O'  C
'78 Mazda RX7. (someone please buy me!)                   ( )   K
'73 FIAT 128 Coupe SL 1300cc.                              U    !
+4 other pieces of junk that will be sold soon 8^).


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