Wide Band O2 + data logger for 84-89 Carrera

[scarceller]

No problem with testing the pump, I accept all ideas.
I have already tested FP following spec. Tested pump engine off (3.4bar). Tested engine running vacuum on (3.0bar) and vacuum off (3.5bar). Also tested current draw (5.1amps). As I already mentioned the FP tests came out 1bar above spec (3.5bar) because PO altered the requlator. The real question is: is the pump producing enough fuel at WOT? and this is harder to figure out. I will try to place the FP gauge where it can be seen while driving at WOT - this will be the best way to see what's going on at WOT at 3000RPMs and higher. I think the pump may just be weak and has trouble delivering enough fuel at WOT, just need to prove that. Testing FP at idle or unloaded engine does not give the entire picture of the pumps performance.
Thanks for all the good information.

Originally Posted by ischmitz

Hm, without trying to sound like a broken record I would try and do the flow test and the pressure tests as described in the Porsche WSM (a:engine running, b: engine runinng, vacuum disconnected). This should give you a basic idea about the fuel pump and its ability to deliver enough fuel and enough pressure.

Next, I fully agree with Steve in that you should probably revert back to stock (pressure regulator, mapping) and then consider a tuning from there. Steve does excellent work in this field.

84porsche9113.2, sorry if I offended you. This wasn't my intention. I simply wanted to point out that there are a number of tests that should be performed to check whether fuel pressure and delivery rates are in spec. Next, to isolate transient problems one has to get more inventive and monitor fuel pressure under varying load and load spikes.

Cheers,
Ingo

[ianc]

Sal, I agree you should revert to the stock regulator. It sounds like Steve will be happy to reprogram your chip with the stock settings, or use the stock chip for testing.

If you have non-standard settings, your results (particularly those relating to the injector tests you intend to run) will be called into question. Additionally, the higher fuel press you're running may well have led to your pump's early demise...

ianc

[scarceller]

I ran a fuel flow test last night, I just attached a hose to the port on the drivers side fuel rail (same port you check fuel pressure) then kicked the fuel pump on by directly applying 12v to the fuel pump fuse (Fuse #3) in the front trunk. I ran the pump for exactly 30seconds and I then measured the fuel amount. I measured 60oz this seems to be twice as much as the .89l (30oz) you shared in your post. Where did you get the .89l/30sec spec? I have the "911 Carrera DME-TESTING PLAN" manual it it does not list fuel flow, it only lists fuel pressures.

Just kind of strange I got exactly twice as much fuel as you speced?

I still suspect my pump at WOT and am in the process of bringing the fuel pressure gauge into the cockpit (just for testing at WOT).

Thanks for all the info so far.

Originally Posted by ischmitz

Actually, the fuel pressure is regulated by a pressure regulator in the fuel circuit. Pressure is raised as manifold pressure raises (to help providing the required fuel under load). The pulse modulation alone on the injectors does not have enough dynamic range to cover everything from idle to WOT at max. RPM.

I think you should check whether that pressure regulator is working properly. The specifications are:

engine off, fuel pump running: 2.5 bar (36 psi)
engine running: 2.0 bar (29 psi)
engine running, vacuum hose disconnected (simulate full load): 2.3 - 2.7 bar (33-39 psi)

The fuel pump should deliver 0.85 liter/30 sec. (0.9 qt.)
The fuel pump should draw between 4-6 Ampere when running

That is a lot to check before jumping to conclusions. Seems like a mechanical gauge would be a good start....

[hcoles]

Sal, on another post and per Steve Wong the mass flow door fully opens at approximately 5500rpm. Will be interesting to see what you get. When I put an LM-1 on my car at the upper rpm ranges it got richer and richer dipping into the 10's. This is where we are throwing away power.

[ischmitz]

Sal, the spec comes out of the Porsche wokshop manual.

[scarceller]

you have something wrong if you dip into the 10.0AFR range at WOT, what RPM?
I have done WOT run right up through 6000RPM and I see nice straight line about 12.8 to 13.2 at WOT between 3000-6000RPM here is an example run 2nd gear with a shift into 3rd.

Green=AFM % door is opened
White=RPM
Purple=AFR
Orange=WOT switch



As you can see my AFR is around 13.0 in 2nd gear from 3-6k RPM then in 3rd gear it remains around 13.0.

Also note that my AFM tops out at about 5500RPMs

Originally Posted by hcoles

Sal, on another post and per Steve Wong the mass flow door fully opens at approximately 5500rpm. Will be interesting to see what you get. When I put an LM-1 on my car at the upper rpm ranges it got richer and richer dipping into the 10's. This is where we are throwing away power.

[jbrinkley]

that pump puts out a constant volume through stock sized lines. To me, if I saw a bigger volume in the same time frame I would assume the fuel pump to be in spec. Don't forget that that pump pumps the same amount at idle as it does at WOT.
If you want, I have a stock FPR that worked well when I took it off that I'll send you for free if you want.
One other thing, if you have a gauge on the rail, pinch off the return line back to the tank while the pump is running, you'll see a spike on the gauge, this in itself will verify that your pump is fine.
I honestly don't know how high the stock pressure should be at WOT under load, but I imagine it isn't more than about 50psi + or -
Just for reference, I run that stock pump in my car and regularly see 70 psi+ or - on full boost.

Setting up an electric sender with gauge would be a waste of money, unless you could borrow one from someone. If you decide to set one up you need this
two adapter fittings from BATinc.net to intercept the soft line return from the rail.
a small section of -6 fuel hose
four dash six hose ends
an 1/8 inch fuel tap with -6 ends
one electric sender with gauge (0-100psi) from egauges.com

[scarceller]

Well I'm not sure why I I'm getting 60oz of fuel in 30 seconds? Any thoughts on this from anyone else would be helpful.

I ran the test because I though it would be worth testing. Right now I'm not that worried about this test since what I really want to know is what's going on with fuel pressure at WOT above 3000RPMs. I think that since intake manifold pressure will be at it's lowest point during WOT and this pressure is tied to the FPR via the vacuum line it will be as if no vacuum or very little vacuum is applied to the FPR wich means the FPR will attempt to raise the FP by .5bar. We shall see.

Originally Posted by ischmitz

Sal, the spec comes out of the Porsche wokshop manual.

[scarceller]

Jerry,

Thanks for the info. I'd take your stock FPR if you are willing to part with it, please PM me with your phone #.

Also, I have pinched the return line from the FPR and my pressure climbed to 5bar almost instantly and was still climbing, I unpinched the line once I saw 5bar.

I plan to just simply plumb my fuel pressure gauge to the cock pit via a long hose for testing. I can't afford the expense of the electrical type gauge just to run one simple test. I just wish to see what the FP does at WOT and go from there. My hope is it actually goes up because at WOT intake manifold pressure is at it's least and would be as if you pulled the vacuum line from the FPR, I think you get the idea.

I'll keep you posted.

Originally Posted by jbrinkley

that pump puts out a constant volume through stock sized lines. To me, if I saw a bigger volume in the same time frame I would assume the fuel pump to be in spec. Don't forget that that pump pumps the same amount at idle as it does at WOT.
If you want, I have a stock FPR that worked well when I took it off that I'll send you for free if you want.
One other thing, if you have a gauge on the rail, pinch off the return line back to the tank while the pump is running, you'll see a spike on the gauge, this in itself will verify that your pump is fine.
I honestly don't know how high the stock pressure should be at WOT under load, but I imagine it isn't more than about 50psi + or -
Just for reference, I run that stock pump in my car and regularly see 70 psi+ or - on full boost.

Setting up an electric sender with gauge would be a waste of money, unless you could borrow one from someone. If you decide to set one up you need this
two adapter fittings from BATinc.net to intercept the soft line return from the rail.
a small section of -6 fuel hose
four dash six hose ends
an 1/8 inch fuel tap with -6 ends
one electric sender with gauge (0-100psi) from egauges.com

[DW SD]

Sal,
Is there any chance your tank is not vented properly? I've seen scenarios where the venting isn't setup right and it places more load on the fuel pump. If no vent, it forces air to leak in at the fuel cap, which isn't meant for such. That could explain your potential low fuel volume at empty tank (vacuum has built up in the tank)? At an extreme, the tank can actually begin to collapse from air pressure.

Doug

[scarceller]

Doug,

With this car anything is possible! It's a nice car but I've found some real strange issues so far. I get what you are saying and I'll take a look to see that the venting is correct. Any tips for what should be checked? thanks.

Originally Posted by DW SD

Sal,
Is there any chance your tank is not vented properly? I've seen scenarios where the venting isn't setup right and it places more load on the fuel pump. If no vent, it forces air to leak in at the fuel cap, which isn't meant for such. That could explain your potential low fuel volume at empty tank (vacuum has built up in the tank)? At an extreme, the tank can actually begin to collapse from air pressure.

Doug

[DW SD]

First, I'd just find it. The vent line is typically attached to the metal filler neck in the front trunk. Trace it? Or remove the vent line at the metal Y in the filler neck to make sure it is venting.

At low fuel levels, see what happens when you remove the filler cap. If it lets a lot of air in, it is likely building up a vacuum.

Doug

[ischmitz]

Originally Posted by scarceller

Doug,

With this car anything is possible! It's a nice car but I've found some real strange issues so far. I get what you are saying and I'll take a look to see that the venting is correct. Any tips for what should be checked? thanks.

Go for a spirited run (best with you tank nearly empty), come to a full stop with the engine still running and then remove the gas cap. If it makes a big sucking noise you know it had vacuum and something is clogged in the venting line.

BTW: The fuel pump delivers more fuel against zero pressure then it would against the fuel pressure in the car. This is why you see 60oz.

Pressure and flow rate are similar to voltage (pressure) and current (flowrate) in an electrical circuit: If you short out a battery (running your fuel pump into the bucket) it will flow to its maximum rate (highest current) but at the same time the pressure will be zero. If you pinch it off (have an open circuit) the pressure will raise to its maximum (open circuit voltage on a battery) but no flow occurs (no current). As long as the pump delivers more that the minimum 30oz and it can get the pressure up it is by all means fine.

Ingo

[84porsche9113.2]

Originally Posted by ischmitz

Go for a spirited run (best with you tank nearly empty), come to a full stop with the engine still running and then remove the gas cap. If it makes a big sucking noise you know it had vacuum and something is clogged in the venting line. Ingo

Hey guys, I know you are trying to solve sal's problem, but as a tangent, it seems you're saying the fuel tank should NOT be pressurized? Is that correct?

The reason I ask is I switched over to this convenience gas cap which has a flap, so I don't have to remove the gas cap or find somewhere to put it. (pretty dumb, but I used to loose my gas cap in the past because I left it on the gas pump). I just pop the flap on the car, and stick the nozzle right in. The cap is made so that it has a spring flap that retracts when you stick the gas nozzle in. Since this cap is not air tight, it does let in air past it....

I know this is a tangent, but is there any detriment to using a cap like this?

Anyway, I hope Sal figures out the problem.. But I was just curious since this was mentioned.

Would switching to a cap like this help Sal at all (is there any difference venting through the filler line vs. the vent line)??

[DW SD]

84-
What happens to your flap if you crash and flip over?
Gravity should not be the primary motive to maintain fuel in your tank. Plan for the worst, hope for the best.

When I installed my fuel cell vent, I added a rollover valve in the vent line. It is supposed to seal off fuel in the event the car were inverted.

Doug

[84porsche9113.2]

Originally Posted by ischmitz

84porsche9113.2, sorry if I offended you. This wasn't my intention. I simply wanted to point out that there are a number of tests that should be performed to check whether fuel pressure and delivery rates are in spec. Next, to isolate transient problems one has to get more inventive and monitor fuel pressure under varying load and load spikes.

Cheers,
Ingo

ischmitz - absolutely no offense was taken! you just made an informative statement about how the FPR works in the fuel circuit, and I just wanted to inform you that I thought both I and probably sal were aware of those facts before making the suggestions that were made and while going about the discussion at hand. that's all. the specs/values you posted though were clearly new information to me and I was not aware of those values. That was very good information and I did not mean to say that I was aware of the other information you posted as well. thanks for the concern!

[84porsche9113.2]

Originally Posted by DW SD

84-
What happens to your flap if you crash and flip over?
Gravity should not be the primary motive to maintain fuel in your tank. Plan for the worst, hope for the best.

When I installed my fuel cell vent, I added a rollover valve in the vent line. It is supposed to seal off fuel in the event the car were inverted.

Doug

Okay, so from what I gather, with this aftermarket cap, I am probably slightly worse off than people who do not have a rollover valve in the vent line?

If I were to crash and flip, I suppose my gas would empty faster, but the other "stock" cars without rollover vales in the vent line, will still have their gas spilling out the vent line as well, correct?

I know what you are saying and I probably shouldn't be taking any chances. But right now this is a 100% street car which is rarely driven. So to me the convenience of the cap seems to outweigh the risk that I may crash and flip over.. If I was racing this car I probably would decide to use the stock cap as it would seem the chances of flipping would be greater then.

[scarceller]

Doug,

I found the vent and it's hoses. Bottom line is the vent into the tank is completely open and the hose vents to a black tank behind the drivers head light. The black tank seems to let air out of it (and into the fuel tank) easily but has some sort of valve that restrics (not totally) air from leaving the fuel tank into the black box. So it seems the fuel tank can obtain a sort of positive pressure but can't ever obtain a negitave pressure (vacuum).

Later tonight I plan to take the black tank out of the car for further inspecion.

Does what I found so far make sence?

Originally Posted by DW SD

First, I'd just find it. The vent line is typically attached to the metal filler neck in the front trunk. Trace it? Or remove the vent line at the metal Y in the filler neck to make sure it is venting.

At low fuel levels, see what happens when you remove the filler cap. If it lets a lot of air in, it is likely building up a vacuum.

Doug

[scarceller]

OK, finished looking over my fuel tank vent and all looks well.

But I found a restrictor device in the vent hose see these pictures:









Here is where the hose goes, it fits between these 2 points:



Kind of interesting, I always learn something new about these cars. This is the 2nd restrictor device I have found in a hose in my 84 Carrera. The other was in the oil breather tube that leaves the oil filler neck.

In the end my fuel tank venting seems just fine.

[hcoles]

Sal, this is a bit confusing...could be almost 2 threads running here... but the dipping into low AF readings at high rpm and WOT is what Steve has said and I think has been cooberated (sp?) with stock dyno runs... maybe others don't dip into the 10's but definately dip well below 12.5 and into the 11's. Not sure why your car is not doing that.... Also glad you also see the the door doesn't open much more after 5500.