Dales944

Hello. My problem is simple to explain - WOT doesn't deliver as much fuel as 7/8 throttle. If I really want to accelerate, I push 100%, then slowly back-off until it hits that sweet spot. First thought was TPS, but after reading the thread archives and Haynes manual, it looks to me as if TPS failure is more common on closed throttle. The ohmeter reads the same partially opened or all the way. So, could it be fuel pump? I know mine has problems - I hear the whirring sound from the right rear underside, especially on hot days. Also, the P.O. let the battery tray rust massively - it had huge gaping holes letting water go right onto the pass floor (I fixed it, yay!). Anyway, I'm sure the DME took a beating from all the water.

OK, sorry this is so long. I would appreciate anyone's insight on my WOT problem. I would love to get it fixed (especially myself). Money is a huge issue for me, as is repair time (it is my daily-driver, so I don't want it to sit at a mech for days).

Thanks in advance.

adrial

How do you know its not delivering enough fuel?
A/F gauge reads lean? smells lean?

Carl Carlson

I'd check the throtle sensor electrical cable. Clean its contacts etc.

Dales944

Adrial, I guess my inexperience/ignorance may be showing here. I don't really know that it's not delivering enough fuel, it just feels/sounds that way (I have no A/F guage). In other words, full throttle accelerates me about as quick as half throttle. It still seems smooth, etc. Doesn't seem to be stuttering or anything, just less pick-up. That is why I "say" it's not delivering enough fuel. Does that help you? I really appreciate your input.

Carl - I'll try that first. Sounds like my price-range!

Thanks everyone.

adrial

Have someone drive behind you when you run through the gears...if they see any blackish smoke...then you're rich...

You can test the fuel pump for flow...should be around 1-1.2L / 30 seconds...To do this on my turbo I disconected the fuel line going to the fuel pressure regulator and let the fuel flow into a bucket for 30 seconds...then measure. You can run the fuel pump by jumpering 2 of the leads in the DME relay socket..they appose eachother...but I can't remember the numbering.

Does it have the same behavior regardless of RPM?

--Adrial

Dales944

Adrial, thanks again! I will try the fuel pump test, the Haynes manual does tell which numbers to use on the relay. I'll also have someone follow me looking for smoke. If I am running rich, could that cause my problem? Also, how do I thin it out? My '83 has no AFR, of course.

Yes, I get the same problem regardless of RPM. ANY time I punch it, I pick-up slower than if I let off a pinch.

Thanks again, Mr. guru.

adrial

If you get the same problem regardless of RPM...I don't think its the fuel pump...because naturally the car uses more gas at higher rpm's...so the problem should present itself at part throttle and high rpm's if it presents itself at full throttle and low rpm's.

Read <a href="http://www.tech-session.com/Paragon/Tech/944_tps.htm" target="_blank">http://www.tech-session.com/Paragon/Tech/944_tps.htm</a> and test the TPS accordingly...

Fuel pressure regulator is another possibility...I know on the 951 it is vacum/boost controlled a little.

That's all I got in my bag of tricks. Hope that helps some...

Dales944

Adrial, once again - THANKS! I'm just glad to have someone offering some knowledge. I read the Paragon piece prior to posting this topic. I indeed have the "bottom-mounted" TPS, so I was hoping not to have to remove the throttle body just to test the TPS. Oh well, you gotta do what you gotta do.

I'm really hoping these several suggestions will fix my problem. This board has helped me with CV replacement, Battery tray replacement, speedo cable replacement, odometer fix, tranny mount diagnosis/replacement, thermal fan switch replacement, fuel filter replacement, and other 944 issues - and that's withOUT me EVER posting a question (these archives are priceless!). As soon as I get my wife to "approve" it, I will pay my dues and become a member.

Thanks again!

Dale

Tabor

While you have your throttle body out clean it out with some carb cleaner. If you are too rich at WOT it could be your FPR. You may want to invest in a fuel pressure guage. <a href="http://www.lindseyracing.com/" target="_blank">Lindsey Racing</a> has one for less than $60. It is a complete bolt on kit.

Dales944

Thanks Mr. Kelly. This is exactly the reason why I posted this topic - all you guys have great suggestions based on experience. Hopefully, with the board's help, I can keep this car running another 19 years.

jim968

Before you do the fuel pump test, it'd be best to eliminate the other stuff. Pumping gasoline out of the car near live electrical circuits is a potentially risky thing.

I've only experienced a couple of failures on these types of pumps; none were reduced delivery volume or pressure. One was intermittent operation, the others just plain quit working.

As always, YMMV.

Jim, almost Friday!!!

Dales944

Jim (Mr. 968?) I respect your opinion. I've read to put some towells down by the rail in order to absorb any excess. So far, the pump test is on the bottom of my list (simply because it's the most invasive). What is YMMV??? I'm new to this stuff. And yes, TGI almost F!!!

adrial

"Your mileage may vary"

I need to get out of the hhouuussseeee..... <img src="graemlins/crying.gif" border="0" alt="[crying]" /> <img src="graemlins/crying.gif" border="0" alt="[crying]" /> Ribs I feel your suffering...my buddies left for college and I'm still home.

Dales944

Adrial, HUH?

adrial

hehee
YMMV = "your mileage may vary"

woopsies