2.8 fuel problem

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owenamber
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2.8 fuel problem

Post by owenamber » Mon Nov 25, 2019 8:28 pm

Hi
I have a 2.8 which stars fine and ticks over nice. When warm however it just cuts out and is then reluctant to start. When it does start with a struggle it will back fire and cut out.
Any suggestions appreciated.

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Andrew 2.8i
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Re: 2.8 fuel problem

Post by Andrew 2.8i » Mon Nov 25, 2019 8:43 pm

owenamber wrote:
Mon Nov 25, 2019 8:28 pm
Any suggestions appreciated.
Possibly a fueling issue?
Have a read of this extremely useful page to familiarise yourself with all the different elements of the Bosch K-jet system.
https://www.zeepoort.nl/jetronic/K-Jetr ... oting.html

At the bottom of the page there is a troubleshooting section you can work your way through.
:goodluck:

Andrew.
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Bug
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Re: 2.8 fuel problem

Post by Bug » Mon Nov 25, 2019 9:00 pm

owenamber wrote:
Mon Nov 25, 2019 8:28 pm
Hi
I have a 2.8 which stars fine and ticks over nice. When warm however it just cuts out and is then reluctant to start. When it does start with a struggle it will back fire and cut out.
Any suggestions appreciated.
Has it been 'tuned' by anyone recently?
If so it may well be running weak. Will run ok until warm as the Warm Up Regulator will compensate.
The two exhaust pipes don't both run the same.
If the gas tester is stuck up the richer pipe and it's adjusted to that then the other bank will be on fumes.

I've covered this many times before, but the best way is to measure both pipes for emissions, then set the average between the two pipe of 2.8% CO. (ie, could be one reading 2.4 and the other 3.2)
You may be told this is too high, but I ran my 2.8i for 26 years and it always responded best to this method.

Of course, it could be one of many other reasons, but you could always start with this.

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Re: 2.8 fuel problem

Post by Peter-S » Tue Nov 26, 2019 12:29 am

If it hasn't been done for a while it is probably worth starting with a new fuel filter. Plenty of other possibilities but that is a simple one to discount.
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owenamber
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Re: 2.8 fuel problem

Post by owenamber » Tue Nov 26, 2019 8:39 am

Andrew 2.8i wrote:
Mon Nov 25, 2019 8:43 pm
owenamber wrote:
Mon Nov 25, 2019 8:28 pm
Any suggestions appreciated.
Possibly a fueling issue?
Have a read of this extremely useful page to familiarise yourself with all the different elements of the Bosch K-jet system.
https://www.zeepoort.nl/jetronic/K-Jetr ... oting.html

At the bottom of the page there is a troubleshooting section you can work your way through.
:goodluck:

Andrew.

Hi Andrew thanks for that

owenamber
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Re: 2.8 fuel problem

Post by owenamber » Tue Nov 26, 2019 8:43 am

Andrew 2.8i wrote:
Mon Nov 25, 2019 8:43 pm
owenamber wrote:
Mon Nov 25, 2019 8:28 pm
Any suggestions appreciated.
Possibly a fueling issue?
Have a read of this extremely useful page to familiarise yourself with all the different elements of the Bosch K-jet system.
https://www.zeepoort.nl/jetronic/K-Jetr ... oting.html

At the bottom of the page there is a troubleshooting section you can work your way through.
:goodluck:

Andrew.
Thanks for that

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Re: 2.8 fuel problem

Post by 340truck » Thu Nov 28, 2019 9:43 pm

You MUST use a gas analyser to set he idle mixture on a 2.8 - many times on here the method for setting a carbed pinto has been detailed but the K-Jetronic adjustment is so fine that it can't be done by ear. You will see how much the % is changed with the smallest movement on the adjuster.

You will have to richen it whilst the warm up reg is working and see if it will idle once it warms then do your accurate setting. If you can't get it to idle at all it's not a mixture problem, look at timing and valve clearances. Probably not a bad idea to do a simple top end engine service anyway - new plugs and leads, check clearances, ignition timing, then mixture. Depends if you just want to solve the problem I suppose.
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Re: 2.8 fuel problem

Post by Bug » Fri Nov 29, 2019 6:33 pm

340truck wrote:
Thu Nov 28, 2019 9:43 pm
You MUST use a gas analyser to set he idle mixture on a 2.8 - many times on here the method for setting a carbed pinto has been detailed but the K-Jetronic adjustment is so fine that it can't be done by ear. You will see how much the % is changed with the smallest movement on the adjuster.

You will have to richen it whilst the warm up reg is working and see if it will idle once it warms then do your accurate setting. If you can't get it to idle at all it's not a mixture problem, look at timing and valve clearances. Probably not a bad idea to do a simple top end engine service anyway - new plugs and leads, check clearances, ignition timing, then mixture. Depends if you just want to solve the problem I suppose.
Whilst I agree wholeheartedly with Mr Truck (mostly cos he's about twice my size :roll: ), I would say that the symptoms are almost identical to mine when the garage had tuned it back to a standard setting on the richest bank.
I too, was led on a wild goose chase, thinking the lack of idle and backfiring was timing. Took me a while to fathom it out.

However, do NOT discount all the suggestions made above. Bear in mind that if your spark plugs wear down, the gap will open up. It may only be a minute change but as the spark has to build up a bit more energy to jump the gap then it effectively retards the ignition (especially if the plug gaps weren't checked when you put them in, as I've always found them to be bit wider than they should be). Same applies to a high resistance in a lead, or across the distributor.

It is never a bad thing to fit new ignition parts first as then you know you're starting from a good position.

As an aside, I always kept the centre HT lead and the longest plug lead from the set I changed out, plus a good plug, in the boot as it'll get you home in an emergency. Do make sure its the longest lead though as it's embarrassing to find your spare is too short.

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Re: 2.8 fuel problem

Post by 340truck » Fri Nov 29, 2019 8:48 pm

It's a while since I saw you Bug...probably 3 times your size now!
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Re: 2.8 fuel problem

Post by Mc Tool » Fri Nov 29, 2019 10:04 pm

Larger plug gaps causes ignition to be retarded ? :python: me thinks your plug gap needs closing up a bit :poke: :xd: ,that's right up there with the misinformation mother's tell unruly kids about what's going to happen if they swallow Cherry stones or chewing gum,.....or don't eat their Brussel sprouts :D
you know it was a goodie when the end is stickin up out of the water

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Re: 2.8 fuel problem

Post by Bug » Sat Nov 30, 2019 8:22 am

Mc Tool wrote:
Fri Nov 29, 2019 10:04 pm
Larger plug gaps causes ignition to be retarded ? :python: me thinks your plug gap needs closing up a bit :poke: :xd: ,that's right up there with the misinformation mother's tell unruly kids about what's going to happen if they swallow Cherry stones or chewing gum,.....or don't eat their Brussel sprouts :D
Really?
Well thank you for enlightening me.
Never too old to learn eh?

Ok, so leave your spark plugs alone. No need to change them as the wear on them is irrelevant.
I hope you read this in time before you waste your money on new ones. :xd:

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Re: 2.8 fuel problem

Post by Mc Tool » Sat Nov 30, 2019 8:47 am

Awe ,now your just being silly







:xd:
you know it was a goodie when the end is stickin up out of the water

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Re: 2.8 fuel problem

Post by stevemarl » Sat Nov 30, 2019 2:11 pm

Bug wrote:
Sat Nov 30, 2019 8:22 am
No need to change them as the wear on them is irrelevant.

The gap is not irrelevant, but it honestly will not affect the actual timing, the spark occurs the instant the field collapses in the coil , gap just affects the quality of the spark, . I`m sure you`re thinking of the points gap which DOES alter timing?

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Re: 2.8 fuel problem

Post by Bug » Sat Nov 30, 2019 7:22 pm

stevemarl wrote:
Sat Nov 30, 2019 2:11 pm
Bug wrote:
Sat Nov 30, 2019 8:22 am
No need to change them as the wear on them is irrelevant.

The gap is not irrelevant, but it honestly will not affect the actual timing, the spark occurs the instant the field collapses in the coil , gap just affects the quality of the spark, . I`m sure you`re thinking of the points gap which DOES alter timing?
Then we shall agree to differ and leave it at that.
Never had points in my 2.8i. That much I am certain of. ;)

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