Only starting with injector pulled

[stallie]

As the title says, my starting woes continue. I thought I'd fixed them with the neg terminal, alas no.

 

Once running, she's going beautifully; idling happily around 800RPM when up to temp, accelerates smoothly with a size 11.

 

However, she's a bit recalcitrant to start.

 

After sitting for a day or two, she'll turn, cough once, then not catch again. Whether cranking it, choke or no choke, leaving it for a while, then it might catch eventually, maybe not.

 

However, if you pull the injector 1, she fires immediately, then replace the injector and she warms up and all is good.

 

Does anyone have any pointers please?

 

[k_raven_smith]

Check for volt drop on cranking at the fuel pump

[Mike C]

I wired my Bosch directly to the battery via a relay to help cure hard starting. It worked provided that the intervals between starts are less than a week or so- leave the engine longer than that and it still needs a lot of cranking to reprime the injection system.

[AndrewP]

Whats your starting procedure?

 

I have always found that after a bit of a break between starts, the pump needs time to get the fuel to the MU and then to the injectors.

 

For me...run the pump for say 15 - 20 secs with the choke out, turn the engine over and 99% of the time it will fire on 5 if not 6. If not 6, then the last one comes in within 5 secs of the others.

 

As much as the system is a closed system, I guess air gets into the lines over a period of time and so the system needs time to re-bleed the lines of the air and get fuel to the injector tips.

 

oh..and pump voltage as Neil suggests.

Edited December 22, 2017 by AndrewP

[stallie]

The Bosch fuel pump is connected by a relay.

 

I'll check the drop at the pump.

 

Andrew, I've tried leaving it 20 seconds or longer and doesn't make any difference.

[Steves_TR6]

Interesting!

 

Pulling an injector allows more air into the system.

 

The ‘fuel enrichment’ know does two things:

 

1, it pulls on the fuel enrichment lever on the mu to supply more fuel

2, it opens the throttles slightly, if the second cable is connected as many people run without it (i do)

 

So, by pulling the injector you allow more air in, but also more fuel sunce the reduction in vacuum will cause the mu to deliver more fuel.

 

Check the mu enrichment lever is actually operating and the throttles are opening when the cold start knob is pulled.

 

Does holding the throttle open a little help, my car needs a bit of throttle to start, and a bit of cranking of left for a week or more.

 

Good luck !

[Mike C]

There are non return valves in each injector line from the fuel distributor - make sure that they don't have any dirt such as a hair under them.

[stallie]

I pulled the wires off the pump and plugged them into the multimeter. 12.8v when the key is turned, then drops to 11.8 for the first crank. Pause. Next crank Zero. And the next. Leave for a few mins. Prior to crank 12.8, then first crank 11.8, then zero.

 

2 month old battery, never been flat. Fully charged with battery charger a few days ago and has been driving for an hour today.

 

Relay in engine bay.

 

Batt +ve terminal to -30...... 87 to fuel pump thick wire.

Ground to 85 ........ 86 to wire from Fuel cutoff switch

 

Ground from pump via thick wire back into engine bay. Have tried it connected to chassis or to -ve terminal. No difference

[Mike C]

What about the volts into the relay? The battery seems to have enough power to crank the engine. Sounds like a duff relay. Can you bypass it or substitute another one.

[stallie]

Bingo Mike. I found a 20yo old relay on spotlight harness off my old FJ40 I had in my 20s and put it in. Turned the key and it shows 11.8 now on all the cranking! I have also noticed a loud clank from the relay as it receives power - the old one didn't do that. It was 3-4 years ago when I wired the new relay in and seen little use with the car of the road. The motto of the story from the past few weeks is to suspect new parts first, not old. Sad. And don't throw stuff out.

 

I'm thinking that on subsequent cranks, the pump was dropping out but I couldn't hear that over the noise of the cranking..

 

She seems to fire up OK now, but can't tell from cold and with the kids now asleep (9:30pm) I'll be out with the dog tonight if I fire it up in an hour or two to check. I'll know in the morning. Thanks again all, great to be have a brainstorm at one's fingertips. Dan

Edited December 22, 2017 by stallie

[Mike C]

Glad it seems to be working for Christmas. With good quality parts I couldn't agree more-"And don't throw stuff out". I've learned that a lot of new non-genuine electrical parts available these days are just problem creating junk.

[TR 2100]

Not a lot of help with the original question, but . . .

 

Back in the 70s, when I was running/neglecting a

TR6 as daily transport, it was parked on the road

outside (my TR3A rebuild being in the garage).

 

It amazed me that even on a freezing morning, with

snow on the ground, it would start first time.

 

Is that what most TR6 owners expect/experience?

If not, is it down to sub-standard replacement parts?

 

AlanR

[Steves_TR6]

Good news Dan!

 

Alan, the other day i wanted to take the TR6 down to southampton and winchester.

 

At 7am it was minus 3c and the starter barely turned the engine over

 

Started second attempt !

 

Then i had to get the ice off the windscreen :-)

 

Great car the tr6 !

 

Steve

[stallie]

Seems like that was it. Starting perfectly this morning.

 

Merry Xmas all!

 

Dan

[stallie]

As a postscript to this - it wasn't just the relay that solved the problem. Soon after xmas, the problem returned, one cough, then nothing for ages, and pulling an injector seemed to get it started.

 

About two weeks ago, I hooked up the voltmeter again, and again noticed a flicker on the second or third cranks onwards, even though the relay was happily "clacking on with the key. The kids confirmed with their hand on and ear next to the pump that it made funny rat tat tat noises when I was cranking, but it came good before the starter had disengaged so from the front it sounded uninterrupted.

 

I bypassed the inertia cutoff from battery to the relay and the volts didn't flicker - ah ha! . I pulled it out and noticed that on the voltmeter there was not always a circuit when held upright. I pulled it apart and the copper appeared to be quite oxidised - obviously hindering a good circuit. Some wet and dry sanded out all the contacts and two weeks onwards the problem has not recurred. So the vibration on crank must have intermittently been shutting off the relay to the pump.

 

I hope this helps others.

 

Edited January 20, 2018 by stallie

[john.r.davies]

Lucas Pi is usully set up to be rich at a normal start and low speed running, as it tends to weaken at high revs.

Perhaps that helps cold starts?

 

John