View Full Version : OT Petrol/Gasoline Injectors.. Advice Sort

04-05-2009, 09:12 PM
First ...key for Yankees and other non brits

autogas = Propane
Aldi= store like harbour freight on a smaller scale.
LPG system= sequential injected ECU controlled system
AR5E=.work that one out yourselves :)

Cars been off the road for about 3 weeks ..
Preparing for mot .annual test.
got sent the wrong Wheel bearings ..seems all their entire stock of these is the wrong bearings in the right boxes ..not their fault but the fault of the manufacturer.

Anyway..you guys seem to give me better answers than the car forums do ..hense posting here.

The car in question ..is a Rover 420 NASP, is a duel fuel LPG/autogas/ petrol. 84,000 miles

LPG system is injection system fitted by myself 3 years ago.

The fuel pump and remains switched on whilst running on LPG ..and the injectors are turned off........so you still got petrol pressure in the rail.

The last time the car was run on lpg...it was misfiring during the warm up sequence.

Misfiring problems occur on LPG ...very easily ...as everything has to be spot on with LPG ..'cause the stuff is harder to ignite ..because LPG is an insulator and it's hard for the spark to jump the gap.

So, the cars been standing ...I'm doing jobs on it ...I've not started it for 3 weeks ..

So I thought, whilst I'm waiting for parts will change the plugs .. (maybe the misfire was due to these)

Took them out one by one ..they looked very good ..

Got to plug number 4 and it was wet with petrol ...

Remember ..its not been run for three weeks ..
Can I assume that the wetting is from a duff petrol injector ..slowly letting out the fuel pressure thats trapped in the rail ..
is this normal. ....this could have been the cause of misfire overfueling ...duel fuelling on that cylinder.

if the case, its a pain in the ar5e ...means to me, another 18 for the manifold gasket to change the injector ..

and the price of the injector.

I have one of those aldi ultrasonic cleaners ...do you think these will clean injectors ..or is this problem beyond cleaning and due to internal seals .

Do I somehow have to power up the injectors whilst they are being cleaned ..if so how ?

all the best.markj

Rookie machinist
04-05-2009, 09:45 PM
Sounds like you have a leaky injector. I have never had much luck with cleaners, best bet is to just replace the injector.

J Tiers
04-05-2009, 11:50 PM
The injectors are not usually pointed at the plugs.... especially not with "intake" ot "manifold" injection........ so how did the gas (petrol) get on the plug?

Sounds like quite a bit of gas may have been sloshing around in therewhen teh engine was running...... that's the only way I can figure to have the plug wet... leak-down I can't see getting the plug wet with gas.

First try some injector cleaner additive, if you can get it there. Over here the best I know of is "techron", which is apparently naptha (light paraffin) and some other solvent stuff.

But if it keeps misfiring, I think I'd shut it down and not run it until the injector is fixed. if it was that wet in there, it may be washing off the oil.

doctor demo
04-06-2009, 12:07 AM
Mark can You disconnect the fuel pump circut so there is not any rail pressure , and then run the engine on propane to see if the miss goes away?
If it does then try some additave cleaner in the petrol tank first befor tearing stuff apart. Techron is good stuff if You can get it, if not try Lucas inj. cleaner . I have had good results with that also.