Lotus Elan

Slight Hesitation/Bog off idle- Stromberg

PostPost by: bdea » Tue Aug 06, 2019 1:44 am

Hi to all: Could you help me out on this problem?

I have to figure out why the car quit in 92 F degree weather, driving along and it felt like the someone turned off the ignition sw.

Just installed the Pertronix III ignitor w Old MSD Blaster coil...coil was hot to touch at incident. Let it cool, started to catch but died...did coil burn out?

MSD Blaster coil: Primary- 2 ohms / Secondary- 6.1K ohms
Pertronix Flame Thrower III: " - 0.6 ohms / " - 4K ohms

Repairs/Diagnostics:

Vapor Lock? Don't Know!

Did change out to the new Pertronix Flame Thrower III coil as recommended by Pertronix, still no start until I realized the fuel level in the mechanical pump was low...primed it and it started!
(Did not retry Old Blaster coil after discovering low fuel @ pump). Does coil heal itself or was it........

VAPOR LOCK?

Now another problem... off idle, slight Bog and hesitation:
then it rev's normally...


Lowered static timing from 14 degrees BTDC to 11 degrees.

Total advance: 27 degrees BTDC @ 2,400=3K RPM

Dwell analog- via Ignitor III - 9 degrees @ 975 RPM to 40 degrees @ 6K RPM.

Idle with Strombergs 950-975 RPM.

Now, the engine doesn't run on after key is off (Detonation!):

Better but still bogs so slightly (never happened before), also wondered why the car would almost die when feathering the throttle and clutch from a starting stop at stoplight.

Had to rev more the usual when starting off.

Checked for vacuum leaks, O rings, T connection at frame reservoir, temperature compensator, over run valve, at carb manifold/adaptor.

Checked for air valve sticking. 20w-50 oil in damper. No tears in Diaphragm.

Checked Distributor Cap, slight erosion at brass terminal, cleaned and slight discoloration at brown Bosch Rotor. Checked Dwell of Igniter III - 9 degrees at idle to 40 degrees at 6K RPM. 12.4 -14 Volts
Ground at Distributor to Battery resistance= 0.3 ohms

New NGK BPR6ES at .034
Older " " " .044

Spark Plug Leads- 7K -3K ohms

OH, WHAT CAN IT BE?

Many TIA!

Brad
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PostPost by: Citromike » Tue Aug 06, 2019 4:46 am

I?d say the pistons aren?t floating up as they should. I use ATF (auto trans fluid) or less viscous oil like 0-10W.

You could loosen the screws on the carb caps and wiggle it a bit then retighten. Then start the motor and try revving it off idle in neutral.

Perhaps add a bit more timing advance at idle.

Good luck.

Mike
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PostPost by: jcocking » Tue Aug 06, 2019 6:08 pm

combined duplicate topics.
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PostPost by: david.g.chapman » Tue Aug 06, 2019 6:10 pm

If it's vapour lock, pouring some cold water over the fuel pump and pipes should get the fuel to re-condense and the engine will run OK again, and this will confirm the fault. So take some water with you next time you go out.

Also check you get good pulses of fuel from the pump on the starter with the output pipe open. Catch the fuel in a jar to be safe and get someone else to operate the starter.

Make sure the fuel level in the float chambers are ok and that the float chamber input valves are clean and operate properly.

Dave Chapman.
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PostPost by: bdea » Tue Aug 06, 2019 11:25 pm

Jeff,Thanks for combining Subjects, didn't know if it was electrical or fuel issues.

Citromike, motor ran fine w 20w-50 before issues... will check on vapor lock first.

David, Warm to hot tomorrow, will check cold water trick and on myself if I breakdown again! :oops:
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PostPost by: 512BB » Wed Aug 07, 2019 7:01 am

'Also check you get good pulses of fuel from the pump on the starter with the output pipe open. Catch the fuel in a jar to be safe and get someone else to operate the starter'

If you try this, disconnect the HT lead from the top of the coil. These cars catch fire very easily, and heavy fuel vapour in the vicinity of the distributor is not a good combination. Many an Elan has ended up looking like a large black shreaded wheat due to just this senario.

Leslie
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PostPost by: el-saturn » Wed Aug 07, 2019 8:06 am

leslie - your reminder (the lethal one) is a REAL addition/contribution as it's exactly these 3rd priority things you can disregard!! ...................some can say: been there, done that! Sandy (no, didnt happen to me, but seen the results, gfrp is also combust?ble!)
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PostPost by: 69S4 » Wed Aug 07, 2019 8:14 am

Have you tried pulling out the choke when it's bogging? I had a similar experience a year or so back where it wouldn't pull away unless you were on 'full throttle'. Pulling out the choke restored normal service suggesting it was running weak. Exactly why is still a mystery but as it happened straight after I'd overfilled the dashpots with 20/50 I suspect that had something to do with it. Once the excess had been used up it ran fine.
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PostPost by: bdea » Fri May 08, 2020 3:38 am

Problem solved!!!

Sorry I haven't posted my solution earlier, forgot I even asked it before... senior moments!

When the elan got towed, I disconnected the vacuum tee :shock: for the headlights at the front chassis vacuum reservoir fearing the tow operator would break it off when attaching the strap to pull the elan onto the flat bed.

Loose electrical Brown feed wire at regulator that cutoff power to ignition! :idea:
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PostPost by: bdea » Fri May 29, 2020 3:55 pm

Please review my other post on Adjustable Needle to Enlightenment:

viewtopic.php?f=40&t=46826
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