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  #1 (permalink)  
Old 11-30-2007, 08:33 PM
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Default Fuel starvation problem - help!

Took the car out to see if I could get it to play up as it had done on me the last time so that I had a bit more time to try and figure out what was happening.

Filled the tank up to make sure it wasn't a starvation issue from within the tank.

Had pulled up to a set of lights and as I went to take off I lost all power but the car would alternately power up and die every couple of seconds or so. I limped home and it stopped right outside the house and took quite some time to restart but it behaved normally for me to back it into the shed.

I had cruised down the freeway for 15 minutes or so without a drama and was driving back in 60 and 70 zones when the problem started.

I'd also noticed my pumps were reasonably quiet at the start of the trip but at least one had developed a variety of noises.

Reads to me like my scavenge pump is the issue, does this seem a reasonable assessment? Comments please and suggestions perhaps how to test and rectify the issue.

I presume the hard starting in the drive was perhaps from air in the lines to the engine until it had redeveloped a full pipe of fuel and then happily run again.

It's a Carter scavenging pump and Bosch 044 primary and I'm also worried that if the Carter has been failing to provide fuel to the Bosch that the Bosch pump might be at risk of damage too.

I'm under time pressure now to be able to present the car to a mechanic for a RW and to Vicroads for its inspection.
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Old 11-30-2007, 09:06 PM
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Firstly .. why on earth do you need more than one pump? Is that 302 going to suck that much gas? I have seen on a fresh built car bits of paper in the tank that block and unblock the pickup.(happened once to me). I would say use one pump.
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Old 11-30-2007, 09:32 PM
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chanmadd

This is an external pump system thus first pump scavenges tank to a swirl pot and primary pump feeds motor from swirl pot. Swirl pot also takes engine return fuel and can overflow back to fuel tank.

This is the normal set up in such cases.

I do want to go intank fuel pump but that will come when I get an aluminium tank fabricated down the track. Then I can have just one pump.

Until then I have engineering to overcome and reliability to achieve.

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Old 11-30-2007, 11:09 PM
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Just having a thought about connecting the Bosch pump direct to the fuel tank to see if this pump is not part of the problem.

Can anyone see any problems with temporarily testing by this means?

Is there any reason why this wouldn't feed the engine properly?

I'm guessing the reverse opportunity and using the Carter direct will strike problems possibly due to lack of pressure and rate of supply to the engine. But could this be a possible test mode too?

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Old 12-01-2007, 01:02 AM
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Hi Slowy,

I have a 5L Windsor in my RMC and it cuts out too! My car will run fine and then cut out at idle when it is hot. It also has a habit of refusing to start after it has had a run and then been off for a few miunutes. It will always restart in a couple of minutes after the bonnet has been up. I an sure that my problem is heat related as I have a single in-tank pump amd I can hear the fuel circulating when I try to start it. I am still trying to find the problem, so any suggestions would be welcome. I am running an Autronic SM4 ECU and my engine has coil packs.

Ross
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Old 12-01-2007, 02:00 AM
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Default Measure

HI Guys,
Is there a way mount a temporary fuel pressure gauge to take a reading at the fuel rail when you are driving.

It may be a regulator problem rather than a pump problem.

Phil
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Old 12-01-2007, 06:02 AM
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Phil

I did borrow a gauge and ran it in-line on the inlet side. This indicated that the pressure was good and delivery rate was ok, although I suspect the pump was down in performance against its own specs. but well above the engine's needs.

Steve
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Old 12-01-2007, 09:58 AM
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I am sure that you guys are recirculating the fuel ..ie..return line. Check the pressure regulator ,I would agree that sounds the most logical.The factory regulator.. (Is this the one you are using) ..requires vacuum to operate ..Right? Maybe with the hot cams etc the regulator is not working properly at hot idle???
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Old 12-01-2007, 11:48 PM
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Nah

I hooked up my 044 pump direct to engine today and went for a drive in the heat and once the pump started making noises I eventually stopped. A bit of a rest and it would sort of come good again, so I was able to limp home after a second rest but I missed the first V8 start - bugga.

A bit frustating too as I went out this morning with the fellow around the corner building his 2nd GForce and not a problem. Admittedly as I backed into the drive after the shortish trip, the pump started making its noises so I guess it wouldn't have been long before I'd had trouble.

Anyway at least I know my car weighs 1240kg with a full tank and his essentially finished at 1260kg but then he is a darksider. Im assuming my tank holds 50 - 60L so just under 1200kg me thinks.

Anyway, anyone have a new spare Bosch 044 they want to sell, as I'm in the market!!

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at leats
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Old 12-02-2007, 05:31 PM
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Hi Steve,

I'm also using a carter low pressure pump and a 044 high pressure pump. I've had no preblems (except for the time I almost ran out of fuel )

From my limited knowledge I would suggest your 044 pump might be to blame. The pump requires fuel to lubricate it. It might have run too dry while you were sorting out your fuel pump wiring or just turning on ignition while sorting out other wiring issues. I was warned not to use it dry. But given the pumps only operate for 2 secs when on ignition it can be easy for forget about it.

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Old 12-02-2007, 05:55 PM
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Al

It is the 044 that's buggered so am buying new one today and hope to be mobile shortly thereafter.

I do plan to wet the pump before fully installed and switched on, though I asked two suppliers and they had no exceptional concerns for initial startup. Clearly getting fuel into it ASAP is the best action.

How's your build/engineering going?

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Old 12-02-2007, 06:06 PM
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I didn't wet mine, I just primed the pump directly without ignition on.


Final inspection is tomorrow. I have already had an inspection and was given a list by the engineer so I'm not expecting too many more issues as it is built to RCM specs. It's a pit inspection followed by brake test and drive by noise test. My engineer has been pretty quick to get VIN's, usually only a couple of days so hopefully next week it should be registered! My RCM came in at 1180kgs, 560kg front 620 rear or 47.5%:52.5% front to rear.

Last edited by NASSTY; 12-02-2007 at 06:10 PM..
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Old 12-02-2007, 06:17 PM
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Al,

I saw you driving your Cobra along one of the side streets down Morabin direction the other day. I was in my Land Rover and waved but you probably didn't see me.

Must be a good feeling to finally be driving.

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Old 12-02-2007, 06:48 PM
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Quote:
Originally Posted by Aussie Mike
Al,

I saw you driving your Cobra along one of the side streets down Morabin direction the other day. I was in my Land Rover and waved but you probably didn't see me.

Must be a good feeling to finally be driving.

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Absolutely!!

It's a small world. I didn't see you unfortunately. That was probably the first major outing. I was too busy checking gauges, listening for anything unusual etc etc as it was a hot day. No problems. These cobra thingies certainly do attract attention though
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Old 12-02-2007, 08:40 PM
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Well done Al.

If all goes well tomorrow, I will be registered - hence the rapid response to fix my buggered pump.

Admittedly the new pump is faintly making the same sort of sounds which is a worry.

Is there anything critical about the style of mounting on these pumps? I'd been given a fabricated strap that contacts over 180 degrees around the pump but have been bolting to a flat plate. Would this perhaps create internal pressure to cause rapid bearing decline?

I have seen the fabricated alloy holders which encircle the pump hence an even pressure.

Can anyone comment on this point?

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Old 12-02-2007, 09:16 PM
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Unless you've strapped it down with dogs and chains I think it'll be fine..... Perhaps you could put some rubber under it to reduce/spread the load and make it quieter too
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Old 12-02-2007, 10:08 PM
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I used to have a 68 Dodge with a 440. My fuel line was running too close to my headers and the fuel was vapourising in the lines. Only showed up when the engine got warm of course.

So if its not too late consider shielding or moving the lines to eliminate the possibility.
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Old 12-02-2007, 11:24 PM
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Steve,

I used the bright alloy brackets that you can get for the 044. No problems so far. Just make sure the pump is rubber insultated and I don't think you'll have a problem.

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Old 12-02-2007, 11:53 PM
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The new pump has run like the old and I wonder if it is in fact fuel heating that is causing the grief.

The supply and return run under the header and up in front to cross over to the engine meeting the standard connection points. Don't know if in an XR8 there is shielding here. Certainly under the headers I have encased both lines in what is called firesleeve as a specific heat retardant barrier.

The one thing that hasn't happened is my return line emptying to the main fuel tank rather than the swirl pot as it is currently plumbed. This would ensure cooling.

What is the usual effect experienced with hot fuel vapourizing in terms of engine operation?

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Old 12-03-2007, 12:22 AM
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When I had vapourising problems the car started splutering. I thought the car had run out of fuel. The car would surge then splutter and nearly stall then surge again. The motor was not efi (1000cfm Carter).

Running the return line to the tank may/may not as the fuel will be vapourising on the way in (if indeed vapourising is the problem)

It might be worth putting your hand on your swirl pot .....to see if it feels hot to the touch (obviously after the engine has been running for a while)

If you want to run a test I suggest you get some rubber fuel line and run a temporary fuel line to the engine routing it well away from any heat source.

Unfortunately the hose is expensive but it might be worth a try if time is limited.

As you know I have the same motor as you in my Cobra. I am running an in tank fuel pump (ford EB) and my fuel lines run through the wheel arch and into the chasis frame on the side of the car (miles from the under car exhaust). The motor runs fine.
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Last edited by cameron02; 12-03-2007 at 12:26 AM..
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