Pelican Parts Forums - Running problems got really bad after fuel filter change.

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Running problems got really bad after fuel filter change.

Hey all,

Took my 79 SC to my mechanic to resolve a weird stuttering/missing issue in the higher rev range under heavy throttle.
All mix/timing/ignition (new plugs, wires about a year ago)seem to be in spec and good order so he was leaning toward fuel delivery issues. He decided to change fuel filter (which is only about a year old). Now the car is running terrible and he can barely give it throttle. He says fuel pressure is good and the injectors are spraying correctly.

He's a little stumped now and is thinking the fuel distributor is the next to check.
Whadya think?

CIS troubleshooting........

Quote:

Originally Posted by oregonmon (Post 5044578)

Oregonmom,

Ask your mechanic for the control and system fuel pressures. Get the values and post them here. When he said 'fuel pressure is good', that's not good enough in this forum. It has to have a value (number) and start from there. Did he check the CDI? How about vacuum leak in the system? Do you have a Permatune? Keep us posted.

Tony

Tony is right,......your tech needs to check & confirm system and control pressures before doing anything else.

You might simply have a piece of gak in the FPR at the side of the fuel distributor and a check of the above two parameters will help.

We had a similar problem and I found this obstruction on the inlet side of the fuel distributor. You can see the plug that has made its way upward to block fuel flow. I've seen this only once before...and it does cause high rpm fuel delivery problems

.http://forums.pelicanparts.com/uploa...1259804307.jpg

Try a new coil and throw a different set of wires on the car then test. I had same issue - hard throttle and at around 5k rpms I would get a hard miss. I even had brand new oem braided wires on it.

Fuel filter flow backwards? Or fuel leak or sucking air on fuel line or fittings?

check for a kink in the tubing from the wur to the return (supple line barbed fitting)

Mine is 3mm and kinked easily when moving thngs around to gain access.

Thanks guys for your replies. Hey Steve! I'm going to share these thoughts with my mechanic. I've wondered this in the past but how do mechanics feel about bringing forum info to their attention?
Nevertheless I will pass this on, he even admitted he was a bit stumped considering it ran fairly well (besides the high rpm stutter) before the fuel filter change but after it runs horribly.

i just replaced my fuel filter. it had been on the car for, shhh, dont tell anyone here, but about 5 years+. i could barely blow through it compared to even the used one off my brothers 930. i took it apart and plan to do a post about it, but later. anyway, i never noticed any problems due to fuel flow. in fact, icould not tell the difference when i replaced it. i did not see that fuel flow direction would effect anything other than perhaps how it traps dirt. its just a folded paper element glued in a case.
so did he FF fix the high RPM problem or have you not been able to drive it?
get the CP's checked as said
he could have disconnected something by accident. check the vacuum lines to the WUR and dizzy. make sure there is vacuum to the WUR at idle. did he verify the advance is working.
did he verify the fuel delivery of the FP?
did he check the fuel volume for equal volume for all 6 injectors. i found a bad plastic injector line causeing my high rpm problems. tony has a neat setup for doing this, although i think i would make 2, each with 3 bottles so i could put one on each side. i just used 6 of the same size cups. it was a big difference for the one that was low volume.

do you still have the bronze filter/screen inside the tank?
Bill K

Well my mechanic ordered a valve rebuild kit for the fuel pressure regulator I believe and will be taking the fuel distributor off and trying to clean/flush it out. From what he said, the fuel distributors never go bad, lets hope so because he said you can't really rebuild them. When he checked there was 1 in the country and they cost around $1000.
So hopefully he finds some "gak" as another tech put it. ;) and it gets flushed from the system or something simple like that. Hoping to get the good word tomorrow but we will see.

Ryan:

Au contraire: http://forums.pelicanparts.com/porsche-911-technical-forum/272657-cis-fuel-distributer-cleanout-w-pics.html.

Now this project represents a meaningful amount of time that you may or may not be willing to pay.

I am still willing to bet that it has nothing to do with fuel delivery and that it is ignition related. Coil, wires or dizzy is culprit.

Any takers? :eek:

Doesn't it seem easier and more economical to try a different set of wires and a different coil? I am sure the shop has some.

Quote:

Originally Posted by mca (Post 5048620)

+1...I will tend to agree that it may be ignition-related. I usually don't pipe in on CIS issues, because many problems seem to be vacuum related. Funny, but I don't seem to see if anyone has tested for vacuum leaks.

FD's do go bad, mainly get gunked up or dirty inside from sitting. dirt is the enemy.

if the vac hose from the WUR to TTV to throtlle body came off, that would make it hard to give it gas. also check the electrical connection on it.

if the plugs are a year old, you might replace them along with cap and rotor.

Just to fill in the ending here. So after the mechanic went through the fuel system and went back to the fuel injectors to look at the spray he started to notice that they were really not doing well in the upper rev range.
So he replaced the injectors and the problem (stuttering/missing) with throttle past halfway is gone.
Woohoo, been dealing with this for a while and now I've got full power back. Almost forgot what it was like.
Thanks all for the replies.

Mark man, pull your self together you`re rambling.

I don`t mind chatting to hairdressers but only when I`m having my hair cut and even then I only want to talk about vacations..... not hair straighteners. :rolleyes:

Quote:

Originally Posted by mark7173299 (Post 5066687)

The first two to be released were the limited edition GHD Dark and the GHD Pure. The new styler were launched with a marketing campaigne that revolved around the question ?Are You Dark or Pure?. The GHD Dark came in a glossy jet black finish and a black heat resistant travel case to prorect your new straighteners. While the GHD Pure came in a glossy white finish with a black heatb resistant case that had a white floral pattern of the outside of the box. These were first revealed at the 2008 GHD expert Awards in London and were then released a few months later.The next new straightener to be released was the Pink GHDS Kiss IV Styler. Every year GHd release a Pink hair straightener in conjunction with Break Through Breast Cancer awareness week. For every hair straightener sold ?10 is donated to the breast cancer charity and salon are encourage to take part in further fundraising events. Every year GHD and GHD salon raise hundreds of thousands of pounds for this worthy charity. This year GHD also decide to take a different spin on there Pink hair straighteners. The new Pink GHD Kiss came in a glossy finish with a free triple lip gloss set and Pink heat protection spray to use with your straighteners.The latest glossy ghdswas the GHD Purple Christmas gift set. This included the new Purple GHd Iv styler with apasiley floral effect, a 1100W Purple GHD travel hair, Purple hair clips and the latest GHD hair styling DVD. All of these items then came in a heat resistant travel roll bag with various compartments that you can use to store your products, straightener ans hair dryer.With the sucess and popularity of the coloured GHDS hair straighteners, it leaves us in no doubt that GHD will again release a new coloured cheap ghds very soon. They question is, What colour will it be?

Hi Mark,

While it certainly sounds like you have an interesting product line, it bears mentioning that many members of BFSFCP (Benevolent Fraternal Society of Follically Challenged Persons) may take offense about being left out.

I would suggest that you offer something like Johnson's Trewax for those souls who wish to "shine".

Best Regards,

That is a big deal indeed did not know how to solve it.