Birty Dastards Jeep Club

Tech Forum => Workshop => Topic started by: marsie on August 13, 2007, 07:27:53 PM

Title: grand cherokee 4.0 starting fault
Post by: marsie on August 13, 2007, 07:27:53 PM

As some of you may know i have recently bought a 1999 wj grand cherokee with LPG.Recently it has developed a starting fault :twisted:

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Post by: Mike Pavelin on August 13, 2007, 07:42:09 PM

There s a seal inside the fuel pump which fails, causing the fuel rail pressure to leak back to the tank when the engine is turned off. This causes long cranking times and eventually poor running. The seal can be replaced but the tank has to come out to access the pump.

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Post by: Bubba on August 14, 2007, 05:29:04 AM

ouch if thats what it is

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Post by: Mike Pavelin on August 14, 2007, 08:51:54 AM

Get hold of a fuel pressure gauge that fits onto the test port on the fuel rail. Run it up and then switch off and watch the fuel pressure. After about 5 minutes there should still be around 20 psi in the rail. If not, the fuel pump is suspect unless there is an external fuel leak..

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Post by: marsie on August 14, 2007, 07:29:06 PM

Checked the fuel at the rail.Got loads of pressure when the engine was running but as soon as it stopped just as spray of fuel then nowt.Turn ignition off then on,got a 2 sec buzz from pump and a spray of fuel then nowt
Has been starting fine today,only seems to be when its hot weather(been a bit cooler today here).Plus even when its left over night it always starts first click??? only has problem on really hot days when engine is upto temp and its left for about 10-30mins  :twisted:

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Post by: Bubba on August 14, 2007, 09:32:24 PM

cam sensors act all funny like that if they are going fubar

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Post by: jeepey on August 15, 2007, 08:24:50 AM

my dads 03 4.0L TJ does exactly the same as what you described . dealers reset the computer and still takes a while to fire up when warm  :? seems abit of a mistery

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Post by: marsie on August 15, 2007, 07:17:09 PM

Hmm? think i will let it develop.If it dunt get any worse i can put up with it :twisted:

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Post by: wazza on August 16, 2007, 11:15:39 PM

have you had any trouble or noticed it running hot?

it could be the temp sensor on the thermostat housing,

it'll be thinking its cold an chucking stacks of fuel in.

it happened on my cherry similar but not as bad as you described, all i did was unplug it, so it thought it was running hot,  an it  kicked the lecky fan in perminant  till i got a replacement. had to plug it back in to start on morning cos it was to lean to start otherwise.

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Post by: marsie on August 16, 2007, 11:50:21 PM

On the guage it usually runs halfway,about 100??
Paul

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Post by: isle of man on August 17, 2007, 07:55:48 AM

temp 2 sensor or whatever it's called the one that sends to the pcm, on the front of the engine.





peter henry

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Post by: Mick O on August 17, 2007, 08:45:41 AM

Sounds a bit like what I had on my XJ.

Stealer had it for 3 days 8)

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Post by: marsie on August 19, 2007, 04:06:29 PM

Where is the cam sensor located,how much £££s and what are they like to fit? May fit one if they arent too dear and see what happens.Been running really sluggish today,no missfires or owt just seemed down on power?
Paul

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Post by: Mike Pavelin on August 19, 2007, 04:10:09 PM

If it's a 4.0 it's where the distributor used to go on the r/h side of the engine block near the oil filter, if it's a 4.7 it's on the underside of the r/h cylinder head. I'd still fit a pressure gauge to the fuel rail and check it properly though.

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Post by: marsie on August 19, 2007, 04:32:58 PM

Cheers Mike,dont think its fuel presure cos its the same when running on LPG,Tried switching today between LPG and petrol but it was sluggish on both :?
Paul