| T O P I C R E V I E W |
| Bj011 |
Posted - 29 Oct 2012 : 8:53:38 PM
Hi I have a vn commodore 1989 sedan I had a fuel pump die I replaced it and everything is fine pressure etc but when I accelerate the car doesn't want to go but if its not in gear it will rev fine like it will idle fine in or out of gear but as soon as I pump the gass it seems like its starving for fuel I never had this problem b4 the fuel pump died?
Coil pack is fine, starter motor fine, spark plugs are fine, injectors are fine, filters are fine ..,
Could there be a problem with In the engine?
If any one could help would be much appreciated thanks. |
| 13 L A T E S T R E P L I E S (Newest First) |
| Tim |
Posted - 25 Jun 2017 : 09:46:57 AM
Hey Guys, just picked up an old VN with a suspiciously similar issue to that described in this thread.
Last guy parked it up because it had developed this issue.
It idles just fine but when I put it in gear and try to drive away it bogs down , sometimes it misses but more often that not it simply sounds like its starving fuel. Last guy changed plugs and leads before getting fed up. Yesterday I tried replacing, coil packs, fuel regulator, injectors, fuel filter. nothing has made a difference.
It'll rev up from idle when stationary but probably only rev up to 3500-4000 once or twice before itll start bogging down again.even while in neutral.
Any clues ?
thanks in advance guys.
Tim |
| VNGRPA |
Posted - 31 Oct 2012 : 04:18:13 AM
if it was sucking to much air the check engine light would come on as the map sensor would be reading that there is to much air getting sucked in as its only a 1 bar map sensor same theory as having a supercharger and using a 1 bar map sensor the engine light would come on as its reading to much air in other words if your engine light is not on then its not sucking to much air, what kind of pod filter do you have on it if its a cheap one from super cheap or some were like that then they do sound like there sucking heaps of air but there not really its just the noise of them if its not a well known brand like k&n filters then get rid of it as it wont be doing anything in most cases it takes power away from the engine as its sucking hot air, if you have the stock air filter and case put it on and see if it still makes the same noise |
| kingbucktoo |
Posted - 31 Oct 2012 : 01:43:38 AM
Why do you think your motor is sucking too much air??? You said the car idles fine in Park but not under load.
With some simple maths your car at idle requires approx 1330 litres of AIR every minute. 700 rpm divide by 2 * 3.8 litres.
So I would start looking at the diagnostics codes from the computer. This will give you a hint if its too lean or rich. The VN has no Hot Wire to measure air flow, but just the O2 sensor in the exhaust, MAP & All the other sensors working together to make the motor work. I would start at the source of your first problem the fuel pump.
Did you put the correct fuel pump in the car?? Can you confirm this from the model numbers Next I would look at fuel pressure with a pressure gauge maybe your new pump has a pressure/volume problem.
|
| Bj011 |
Posted - 30 Oct 2012 : 10:34:34 PM
Cheers mate, would a stuffed sensor make it suck to much? Cause I have a pod filter and I understand that there there To suck more then a standard box filter, but this one is sucking way to much air the pressure of fuel is fine but the air is sucking extreme like I have the pod filter then a straight pipe to the engine no cracks etc so
I'm not sure |
| Mechknight73 |
Posted - 30 Oct 2012 : 10:21:19 PM
Sometimes it's as simple as an air leak, outside of the circuit of the air flow meter. I once saw this on a Land Rover V8 running on gas. The salesmen thought it was an ignition problem, because every time you put your foot down, it would cough and fart, and refuse to take off. Curious, I lifted the bonnet and immediately told them where the problem was; the gaffer tape around the flexible pipe just behind the throttle body. As air was rushing in behind it, it confused the air flow meter, and the ignition timing (electronically managed) was way off because of it. Check the intake system from the filter box right up to the intake manifold. If you find anything split, perished or otherwise disconnected, repair or replace and see if it makes any difference. |
| Bj011 |
Posted - 30 Oct 2012 : 10:05:19 PM
What would cause a throttle body to suck to much
Air? |
| VNGRPA |
Posted - 30 Oct 2012 : 9:03:40 PM
the car shaking could be a few things first you will have to tell were its coming from ie front wheels,strut top bearings,steering wheel,transmission mount,drive shaft,rear axles, eg if your steering wheel is shaking then it could be your steering rack,strut top bearings etc, one of the most common reasons why a vn will start shacking at that speed is the drive shaft rubbers are old and perished, get under the car and see if you can move it if you can move it up and down side to side the when your driving it will vibrate and cause a shaking affect |
| VNSVLE |
Posted - 30 Oct 2012 : 8:52:41 PM
Shake sounds like a wheel alignment issue as for the engine issue did you replace the fuel filter after the pump failed??
When checking fuel pressure did you check it under load as well as at idle?? |
| Bj011 |
Posted - 30 Oct 2012 : 7:13:28 PM
How can you stop a throttle body from sucking to much air I know there are bigger ones to suck more but iv noticed that the throttle body is sucking extremely to much air cheers for your help guys
Have another question my car shakes around 80-90km mark, when you accelerate the cars fine even when you stop accelerating at 60-75km but after you hit 80-90 km the car shakes when your not accelerating but if you keep accelerating the car does not shake when I mean shake I'm talking extreme shake, any ideas to help him out cheers. Still talking about the vn commodore ... |
| Mechknight73 |
Posted - 30 Oct 2012 : 4:12:45 PM
So the engine is running smoothly despite being sluggish? This does make a difference in diagnostics. If the engine was misfiring and running rough as guts when under load (as in in Drive) there could be trouble with the ignition. Dodgy spark plug leads often cause that.
If the engine runs perfectly smooth, but lacks any kind of power, then VNGRPA is probably right. As a clue, check the general condition of the exhaust system. If it looks so old as to be the original exhaust system, including the catalytic converter, then it might be time for a change |
| Bj011 |
Posted - 30 Oct 2012 : 11:03:14 AM
Hi thanks, before I try that thought I'd let you know that there are no blockages from the tank to the engine the fuel pressure is fine so I'm just a tad confused as the car was beautiful before the pump died but now it just won't run poperly,
Ill explain how it is working ...
Ill start the engine whole in P for Auto- and I can rev the car but if I put it into D to drive away it seems to slugg off and won't let me put my foot down I have checked the injectors the fuel valve under the car and the filters
There must be a problem from somewhere els Even though none if this was happening before the fuel pumps died. Thanks |
| VNGRPA |
Posted - 30 Oct 2012 : 03:22:11 AM
sounds to me like your catalytic converter is blocked when these get blocked it wont let the car drive or rev it you pump the gas peddle you say (when I accelerate the car doesn't want to go but if its not in gear it will rev fine like idle) easy way to know and tell is it will fell like the motor is straining to rev or get fuel when this is not the case, easy way to tell is to take off the catalytic converter and start the car up (it will be really loud) and rev it if it revs fine problem solved, i would also be checking what Mechknight73 said as when your fuel pump is o the way out just before it dies it will drag dirt and crap through the lines and block them causing the same effect |
| Mechknight73 |
Posted - 30 Oct 2012 : 02:42:12 AM
At the back of the intake manifold, there's a small vacuum servo with the fuel line going through it.About 30mm in diameter, with one vacuum line and the fuel line hanging off it. This is the fuel pressure regulator. Sometimes when you have shale and crap in the tank, it can choke up this servo, bugger the fuel pump and coke up the fuel filter.
There's an inline fuel filter about 70mm in diameter under the car. When you take it off, remember to point the fittings and the line away from you, unless you want a shower of fuel.. Take this filter off, and blow through it. If you feel a lot of resistance, change the filter and see how it goes. If it still causes trouble, check the fuel pressure regulator. If it STILL causes trouble, then you might have to call in the grease monkeys |
