Developed a Starting Issue

Troubleshooting
1

Hey all,

I have been having a strange issue with the car lately, that I would like to share with you, hopefully we can get to the bottom of it. The car is 1991 Auto NA.

Recently the car has developed this starting issue, it used to start up fine, but sometimes it takes a few cranks, and sometimes it wont start at all.
Few times it has cut out, like waiting at redlights, or sometimes It cuts out after 5 seconds of starting, sometimes after 30 seconds. Most of the times its fine.

I have also noticed it is sluggish sometimes, when I put my foot down, it takes its time. But other times it goes like a rocket.

The thing I have noticed the most is that it wont start again, after a long drive. Lets say I drive it none stop for an hour or so, then leave it for a bit, then it wont start again.

If it does, it cuts out.

The things that are new on the car:

  • New alternator
  • New spark plugs
  • New HT leads
  • New starter
  • New radiator
  • New thermostat
  • Refurbished ecu (tried 2 of them)
  • New alarm (nothing invasive, it only has crank cut out)
  • New fuel filter
  • New gaskets (rocker covers, plenum)

I have checked the fuel pump, it has power, and I can hear it run when cranking.
I have checked the pinouts on the IAC all seem to be fine 30 Ohms across all pins.
I can hear and feel the IMF relay click, so I don’t think that is the issue.
Car starts great when cold, even starts great when warm, just sometimes it doesn’t.

I am running out of things to check, the only other things left are the fuel regulator and the injectors.
If anyone has experienced this or has Any advice would be highly appreciated, as its driving me mad.

2

Same thing happened to me , I removed IAC from throttle body and used toothbrush to remove carbon build up on little cogg , no problems since

3

Before I read the list of changed parts I would have guessed a clogged fuel filter :slight_smile:

You need spark and fuel, and oxygen. Oxygen should not be the issue.
If the car “bogs down” when you push the gas pedal, that could indicate its not getting enough fuel (because you open the oxygen port with the throttle so without more fuel the engine runs lean and might stall).

When you give it some throttle, does it smoke black? If so that would indicate too much fuel. Which could explain why it does not start since it could mean the spark plugs are wet.

Are you using original type spark plugs? Have you checked if they indicate lean or rich fuel mixture?

Final question… are you sure your battery is good?
If its bad that could mean you are not getting enough spark during cranking (hard to start) and possibly even stall the engine while at idle due to low output from the generator at low RPM. Bad battery could also weaken your spark as you give it throttle, making the car respond with low performance.

4

That’s a good idea, I did remove the IAC to check the pins it was pretty dirty, I didn’t clean it but I suppose its worth a try. I’ll do that tomorrow.:+1:

5

Yea the plugs are original ones NGK. There is no smoke of any kind, and the battery is good.
It has no issues cranking and there is no miss-fire.

6

Can the ecu be playing up??

7

Well I don’t think so, as I replaced all the capacitors in the original ECU that came with the car (even though it wasn’t leaking), and that didn’t help, so I bought a refurbished ECU , that still didn’t make a difference, so I doubt it’s the ECU.

8

Yeah if you changed those, then it absolutely should be good… :thinking: a proper headscratcher

9

I am sorry to say that listening to the pump making a noise is not a way of confirming that it works OK. The pump is tested by pressure and incorrect pressure will result in running issues. A common cause of pump pressure being low is a result of leaving a car standing for long periods without the pump being submerged by fuel. You will find that water moisture builds up in the fuel tank and the pump rusts inside. This will then lead to no run pump, intermittent pump run and or low pressure. I am not saying that this is the cause of the problem but worth checking, given that you have checked most other causes of your problem.

10

yea you are right Joe, I mean i was in the boot while someone cranked it and i even put power to it with a probe and it ran, but as you say, that doesnt mean it has the correct pressure.
to be honest, i tried to take the pump out, but the fuel line on it is so tight, i couldnt get the nut off and it started twisting the brass pipe. i was scared of snapping it off, even holding it down with two spanners.
i think i will give it another go this weekend.

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11

I’m afraid that the chances of getting it undone at the pump are next to zero. I believe that they use a thread lock on the connection to stop it coming loose. There is a 1 in 25 chance that you can undo it at the other end of the rubber hose but you still won’t be able to get enough revolutions of the hose to remove it. I found that the safest way to get the pump out is to either drop the tank (cheapest option) or cut the hose and fit a new one.

12

Why is this car such a pain in the a#@e :sob::sob:. It’s very unjapanese…
I did think this is on prety bloody tight, the spanner started slipping.
I think I’ll try the bottom nut then if not I’ll drop the tank.
Thanks Joe

13

Feel your pain Cableguy. Been there myself. The cars were high tech back in the 90’s but the ability to do diagnostics easily was primitive and still being develop - OBDII didn’t start til 93. Unless your very skilled with the volt meter, it may be best to convert the 91 to OBDII. I did that to my 92. It will give you a better understanding how the basic stuff is running - ie 02 sensor numbers, % of open throttle position, MAF rate etc. Another help with the obdii was “pending codes” This would happen when something was acting up but was not enough to generate the check engine light. Hang in there. our 3k’s are head turners and when you get your problems solved and you go cruising - it will be worth all the suffering.

14

Update…

So I took out the fuel pump, had to cut the line to get it out, but got it out.
I was expecting it to be rusted and in a horrid state… And guess what it was in almost brand new state, the entire assembly was pristine. But I thought if I’ve come this far, I might aswell swap the pump out. I went for a competition AEM pump, high performance.

Put it all back together, and fired up the car after a week, it fired up Great, let it run, then took for a spin, went to petrol station, came back, started and switched off around another 3 times. It was all fine. Thought that’s it, it’s sorted. 4 hours later, went to take it out to pick up the wife, it started, ran for 10 seconds and it cut out. And wouldn’t start again!!!

What a pain in the ass, I just want to drive it off a cliff now! There nothing left to change it’s almost a new car! :sob::face_with_symbols_over_mouth::rage:

15

Mine was doing that as well. I did all the fuel system stuff but still shut off. My mechanic said it boiled down to timing belt tensioner. I am taking his word for it as it is now running great. Also my harmonic balancer was shot I don’t know if it had anything to do with the issue.

16

Yea I’m not too sure if it’s the timing belt tensioner. I did replaced the rocker covers few weeks ago and I had the cambelt covers off, the tension seemed fine (nothing like Vince’s belt in Joe’s video :joy:).

I have another theory. Trolling through the 3gsi forum, I think it maybe a fuel vapour lock.
Causing blockage in the fuel line. People are getting around it by bypassing the fuel pump resistor.

Edit:
The NA models do not have the Fuel pump resistor, I just found out by looking where its supposed to be and having seen that it does not exist!

17

That I researched as well. It might just be that

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18

Do you have a immobiliser? After market immobilisers are a regular cause of starting problems.

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19

it didnt have one before, I recently installed an alarm, with Crank kill. So it cuts out the starter motor.
But it cant be that, as the engine cranks over.

When the car is cold it fires up great, its only after its been for a decent drive, then stood still that it wont start again. and if it starts it will cut out after 10 seconds.

20

Probs its time to go back to basics and do some diagnostics. For car to run it needs: fuel,air,spark and correct sequence of injecting/sparking

So which one of those is missing when the car doesn’t want to start?

Hearing fuel pump is good but maybe not good enough: pressure? Injectors? Do they work/inject? Do they recieve signal from ECU? Is their resistor in good shape?

Air - unlikely the culprit is in there, even with MAF unplugged it’ll run. And IAC you say tests good. Dunno what else may be in there…

Spark. Here’s where we may have something going on. New HT leads are good. But is the spark present during cranking? Doubtfully all the coils went bust (if one goes down you’d still feel the car trying to start). So maybe track it down to PTU. Is it good itself? And here’s important to check it when the car refuses to start. Cold/warm electronics may show different test results when they’re on yhe way out. Is PTU receiving signal from ECU at that moment?

And speaking of our notorious ECU. The odds are that maybe even those 2 you tried are not good? Did you notice any difference in behaving when swapping (i.e less cases of non start/dying on one comparing to another)?

And grounds… are they all good everywhere?

The fact that on cold it always starts and when warm/cooling down start misbehaving points towards something that when heats up starting acting up. Something tells me it’s related to the electronics or contacts.

I had intermittent non start issues (tho even on cold) when my ECU started giving up the ghost…

My 2pence

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