45 replies to this topic

[CRXer87hf]

Hey guys, I need your help.  I'm having a strange issue with fuel delivery.  As I reached completion of the car I was taking it out on test drives but never really got it over 55mph because they were short test drives on the back roads near the house.  I never had any issues, and the car ran great, or so I thought.  When I finished the car I took it out for a photo shoot and finally got above 55mph.  That's when things starting going wrong.  I had driven it at least 15 miles without issues when I was cruising along at a good clip, the car started to stutter and cough.  It would stutter for a couple seconds then it felt like my fuel pressure was cut in half, not enough to maintain speed.  So I dropped a gear, depressed the clutch, revved the crap out of it, released the clutch while giving it 90% throttle and it would take off.  It would then drive fine for about a minute, and then the cycle would repeat itself.  

 

My first thought was that since the tank had been dry while it sat, its the first tank of gas I've used, and I hadn't changed the fuel filter, I'm sure there's just crap in the fuel system.  So I put SeaFoam in the tank, and replaced the fuel filter.  The next test drive went like a dream.  The car was twice as fast as it was during the test drives where I thought it was running fine.  I took it out on the highway and it went like a bird at 75mph.  Then I brought it home, let it sit over night, and today I took it out and the problem is back again... as if I didn't change a thing!! 

 

Also, I'm not sure that this is relevant to this problem, but if I let the car warm up at first start up, when the car finally drops to normal idle speed, it start rev up and down from 900rpms to 1500rpms.  However when I drive the car for a bit, this problem goes away.  My guess on this is a dirty IACV?

 

So what am I dealing with here?  Is my fuel pump going (it is the factory pile of junk)?  Do I need to drain and flush my tank?  

 

Thanks in advance!!

[niccer]

Stock EW3/4 I assume?

 

The IACV won't have an effect on being low in power when in throttle while moving, but would be something I'd address.  Have you touched anything in/around the intake manifold at all since buying the car?  

 

I don't think it's a fuel pump issue.  That's usually a once and done type of problem and wouldn't be altered by sea foam.(although it could probably be replace since it's an old car)

 

Next in line is the fuel filter.  Replace it, if it's what's been in the car since you bought it, just replace it.

 

Next are the injectors.  They could easily be clogged and not spraying correctly after being so old.  

  

Sounds to me like something is 'gumming up' along the way.  As you shift up in the gears and are in lower RPM's, the load increases and the spark/fuel delivery/timing matters more.  

 

Tell me more about the engine and fuel system.  What have you done to it and how many miles does it have?

[CRXer87hf]

Correct, stock (as far as I know, minus headers and a K&N filter) EW3 with just under 300k on it.  It's been raced in the past and good as everything looks, I suspect it's been rebuilt.  I just changed the fuel filter and it ran perfect for about 20-30 miles, than the problem returned.  The intake manifold hasn't been touched since being in my possession.  *I did have to perform a repair to the hard fuel lines near the fuel pump.  They had rusted through so I had to cut out a section of hard line and replace it with rubber line.  I secured the rubber line with clamps and silicone.  Could the fuel be breaking down any excess silicone and causing it to get into the fuel?  I might just need to drain and flush the tank.  Should I also pull the injectors and soak them?

 

*Fuel line repair...

 

[MichaelStar]

Did you put the silicone into the line?  Gas being the solvent it is, might have eaten away at it a bit.  Also, there is another filter coming out of the tank that I saw in another thread (of course I cannot find it now).  It was a metal mesh one I believe.  

[CRXer87hf]

Yes there is another filter.  I goes in the line the comes directly from the tank to the pump.  When I removed it, it was damaged (not sure how) so I left it out.  Now that I'm reminded of this, I think I may have made a mistake not replacing it.    I kinda forgot about it.

[MichaelStar]

Check the filter up front again to see if it clogged.  There is really no good way to check an injector unless you bench flow one.  

[CRXer87hf]

Will do!  If it's clogged, is there any way I can flush the filter since it's brand new?  I would prefer not ordering another one.  Thanks for your help!

[MichaelStar]

Not really.  The filter material will catch all the crap and the only way to get it out is to get a new one.

[CRXer87hf]

Damn! Oh well.  Better order one then.  

[niccer]

You might be able to back-flow it, but as cheap as they are I'd just buy a new one. 

[CRXer87hf]

Ok, update: Drained the tank, put the cone filter back into the inlet port on the fuel pump, and changed the fuel filter.  On the first test drive it hesitated right away, but after a few miles it quit.  Since then I've put about 150 miles on it.  After about half a tank, it's throws a code.  Haven't checked what the code is, but the car feels sluggish in general.  I just get the impression that it's not getting the correct amount of fuel/fuel pressure.  It's close, but I think it's running lean.  Any suggestions on next steps?  

[CRXer87hf]

Bump...

 

I'm going to tear into it this weekend.  Going to try and diagnose the issue, so all suggestions are welcome!

[CRXer87hf]

So I took apart the entire fuel system in the engine bay, along with the throttle body and fast idle.  I cleaned them and put everything back together.  Prior to me cleaning everything, the idle would bounce up and down slightly, immediately after the car was running at normal operating temp, but after driving for a while it would stop bouncing.  Now it does this all the time (see video below). I also have almost no top end power.  When the secondary throttle plate opens up, it's almost like I have too much air, and it's starved of fuel.  Plugs indicate that it's not getting enough fuel over all 4 pistons.  Thoughts?? Thanks!

 

https://www.youtube....eature=youtu.be

[Quinn]

Have you taken the top off of the FITV and plugged the holes with your finger to see of it goes away? My new build does the same thing if I don't plug the hole in the fitv.

Quinn

[CRXer87hf]

Ok, so here's the latest on this issue.  I was told that air gets trapped in the coolant lines between the Fast Idle Valve and the intake manifold, specifically in the throttle body.  So I ran a hose from the FIV directly to the intake manifold, bypassing the throttle body.  This fixed the issue of coolant not getting to the thermowax in the FIV. 

 

Here is the bypass hose coming from the FIV...

 

 

...and here it is going into the throttle body (black hose with the pipe clamp on it)

 

 

I started the car cold, after this mod, and the idle was high but steady.  Once the car got to normal operating temps, it started bouncing up and down again.  It wasn't as severe an rpm range as before, but there was still an issue.  I then took the top off the FIV and adjusted the seat screw to make sure the valve was seating.  Still bouncing.  So I took out the seat screw and realized that I had damaged the part while removing it the first time.  I had accidentally gouged the seating surface with a screw driver.  Brilliant!  Now, even if the valve is closed, there's tons of air getting by it.  

 

 

So I've contacted Danny at NWCH, and he's going to send me a used one.  Hopefully that will finally fix this issue.