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tmitoraj
Samba Member
Joined: May 10, 2007
Posts: 177
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 Posted: Tue May 23, 2017 5:38 pm Post subject: Making a FI Fuel Pressure Gauge and other FI tools |
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| We all know that that to properly tune a fuel injected Type 3 engine you are going to need a gauge to hook up to the fuel ring to monitor the fuel pressure. Ray G has mentioned many times that he recommends the McMaster Carr Metric Stainless Steel Case liquid filled gauge # 3548K11. What I am looking for are directions on how to to attach this gauge to the injector ring nipple. What parts will need to be assembled to put it together correctly the first time. Pictures are worth a thousand words! Links to components welcome. Thanks Tom |
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Mike Fisher
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Joined: January 30, 2006
Posts: 17970
Location: Eugene, OR
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| Posted: Tue May 23, 2017 9:52 pm Post subject: Re: Making a Fuel Pressure Gauge |
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5/16" fuel hose & hose clamp fits the injector ring nipple. I used a 0 to 100 lb water pressure gauge & brass or plastic threaded and barbed nipple I bought at Home Depot to fit the 5/16" fuel hose too. Nothing that exotic or complicated. Take a 12" piece of 5/16" fuel hose with you to Home Depot or Lowes.
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akokarski
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Joined: May 24, 2004
Posts: 1902
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| Posted: Tue May 23, 2017 10:09 pm Post subject: Re: Making a Fuel Pressure Gauge |
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I thought this was going to a bit more general thread with listing of all needed tools for troubleshooting FI system....
Let's try to take it beyond just the fuel pressure gauge.
low endish model https://www.mcmaster.com/#1798t11/=17rda4c as it uses NPT and you can reuse fittings from regular fuel pressure tester kit or allow you to find 1/4 FNPT to 5/8 barb fitting.
even better gauge: https://www.mcmaster.com/#4240k7/=17qv4bu
For testing MPS and vac advance cannister on distributor, vacuum pump with a gauge is need. My last one ended up being Mityvac from flaps:
http://www.oreillyauto.com/site/c/detail/MTV0/MV80...acuum+pump
you can also use it to check whether aar is fully closing and maybe for few other tasks like bleeding brakes (maybe)
automotive multimeter:
BOSCH FIX 7677
https://www.boschdiagnostics.com/diy/products/professional-multimeter
This will allow you to set/check dwell, rpm and perform electrical checks for resistance of harness, sensors etc. and can be had for $40.
Timing light here is a cheapy from summit with advance capability which you can use to check full advance https://www.summitracing.com/parts/sum-g1059/overview/
for setting timing you can just use non adjustable light and get away with notches on the fan.
another thing i found useful is to get a few injector connectors with pigtails, take out the wires out of the housing and use those when checking sensors instead of trying to poke at the blades directly with multimeter
And of course you will need a set of filler gauges for valve adjustment.
I've intentionally left out tools required for MPS adjustment as there are different types which have different adjustment screws... |
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Donnie strickland
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Joined: December 21, 2009
Posts: 2403
Location: Moody, AL
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| Posted: Wed May 24, 2017 4:19 am Post subject: Re: Making a FI Fuel Pressure Gauge and other FI tools |
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As Mike said, the pressure gauge isn't that complicated.
As far as the other tools --
Tach/dwell/volt meter
VOM
Mityvac
Feeler gauges
Etc.
All of these are needed for any Type 3, not just an FI car. Not trying to be a wet blanket, but there's really only a few FI-specific tools. MPS adjustment is going to be beyond the scope of most home mechanics. If mine needed adjustment I'd just send it to Jim Adney.
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raygreenwood
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Joined: November 24, 2008
Posts: 21520
Location: Oklahoma City
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| Posted: Wed May 24, 2017 6:49 am Post subject: Re: Making a FI Fuel Pressure Gauge and other FI tools |
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| Donnie strickland wrote: |
As Mike said, the pressure gauge isn't that complicated.
As far as the other tools --
Tach/dwell/volt meter
VOM
Mityvac
Feeler gauges
Etc.
All of these are needed for any Type 3, not just an FI car. Not trying to be a wet blanket, but there's really only a few FI-specific tools. MPS adjustment is going to be beyond the scope of most home mechanics. If mine needed adjustment I'd just send it to Jim Adney. |
You cannot "send" your MPS to someone to have it adjusted.
I have an inductive test unit. I can "bench" set MPS's.....however having worked on more than a thousand systems over the decades..... I refuse to do that unless the MPS has been twiddled with by an owner so much that it is too far from nominal to allow the engine to be started and PROPERLY adjusted. In general.....the only condition that will cause this is when someone does not pay attention and hold the inner stop screw still while adjusting on a diaphragm type MPS.
The ONLY thing ACCURATELY adjustable with an inductive gauge with regard to an MPS.....is the inner stop......which sets the maximum lean level at idle to factory baseline so that maximum vacuum at idle does not do three things:
1. Pull the diaphram inward enough to push the armature into the coil far enough to create a lean signal that is beyond the range of the ECU.....which would cause an excessively long period of overly lean mixture as you are trying to accelerate off the line.......or
2. To compensate for the problem listed above......it causes the owner to adjust the main load adjusting screw too far outward to compensate for the armature being too far inward due to the inner stop being misadjusted. Whil this works....it gives excessive enrichment across the board in all other ranges because the baseline spring pressure on the armature will be too low.
3. Likewise related to the last two issues.....it forces you to adjust the outer full load stop too far inward or outward to try to compensate for the excessive off the line lean spot caused by the inner full load stop or excessive enrichment caused by the slackness of the main armature screw being backed out.
On MPS that do not use the copper diaphragm.....all the bench setting can do is get the main armature tension set right and get you in a general range for running. It still needs to be adjusted on a running engine.
This is the equivalent of sending a carburetor off to not only have it jetted.....which can get you into the general range needed for running if the exact engine configuration is known........but also to have it precisely adjusted for exact idle and fuel mixture......which cannot be done on a bench top...... unless its on the engine its going to be run with......with its specific vacuum signature, advance curve, camshaft, exhaust and sensor/network resistance.
With the more advanced fuel injection tssters.....you can see pulsewidth and system response.....but thats not really accurate unless the MPS is attached to the actual system its going into.....and attached to a running engine.
Yeah.....in many cases....and I would not say most cases.......it can get you close.....but not exactly dialed in. Ray |
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Donnie strickland
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Joined: December 21, 2009
Posts: 2403
Location: Moody, AL
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raygreenwood
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Joined: November 24, 2008
Posts: 21520
Location: Oklahoma City
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| Posted: Wed May 24, 2017 8:20 am Post subject: Re: Making a FI Fuel Pressure Gauge and other FI tools |
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Yeah.....and I have adjusted probably as many or more this way.....but they are not adjusted accurately to the engine. You have to tune it in.
I have been ranting about this for going on 20 years.....and people still dont get it. You see endless threads of people trying to get rid of chronic running and tuning problems with D-jet....all while patently ignoring any fine tuning adjustments to the MPS....all blindly following the belief that an MPS unit with the correct part # and a sealed plug in the back is some kind of silver bullet for factory exact running.
Or.....wanting a tweaked MPS set back to magical factory baseline which "should" fix all of their ills. It does not work that way. It assumes the engine vacuum signature and mechanical condition fits an exact profile. It,assumes all engines are opeerated in the same environment. It assumes engines never wear and change vacuum signature.
The system never worked that well. VW, Porsche and Mercedes among the rest....all had warranty and tuning issues as cars aged. About 50k miles was usually the beginning of "odd running" on many engines.
The dealers....outside of probably,Mercedes and mechanics like TRAM......did "0" adjustments. They simply swapped in new parts......which rarely fixed the issue.
By about 1974 Bosch, VW and Porsche started getting wise to the vacuum signature variations and you started seeing new replacement MPS with calibration/grading paint marks and even MPS of known difference from other cars being swapped in to fix issues at known levels.
You also started seeing by the mid 70s....the private mechanics getting even smarter and using the full diagnostic systems to ACTUALLY ADJUST.....the MPS to match the engines they were going onto ....and sctually solve chronic problems the dealers largely could not fix and no longer cared to after about 1976.
Of course Bosch rebuilds them. Rebuilding them is not adjusting them to anything other than the factory ideal baseline.
But hey.....do what you want. I try to get people to learn to understand adjust their own system.
Why?.....because if you are too scared or lazy to do your own adjusting before you send your MPS out to have it adjusted......what makes anyone think you will then not be too scared or lazy to do the fine adjustment required of about 4 out of 5 engines after bench baseline setting.....especially after you just paid $$ for someone to supposedly just adjust your MPS to the "magical" factory setting?
The factory level of tune on D-jet......was just adequate. It ran richer than it should off the line because it was simpler to tune everything in the middle. Some cars ran better than others depending on their individual engine vacuum signature....even though they all ran...... nominally.
If you are not willing to do the fine tuning and drive/testing required to adjust your MPS and your system to run the best it can......there is also no real need to invest in a more accurate fuel pressure gauge.
Why would it help you? If you see your fuel pressure is off by 0.5 psi.....who cares if you are not willing to adjust the MPS to the same level of response accuracy?
If you are willing to adjust the MPS....just do it yourself.
Having someone make sure a tampered with MPS is set to baseline is worth paying for for peace of mind.......but you still need to adjust it by driving and tuning.
And......to do that.....the induction meter and volt meter are not required. Driving adjusting and using a wide band are. Ray |
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Donnie strickland
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Joined: December 21, 2009
Posts: 2403
Location: Moody, AL
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| Posted: Wed May 24, 2017 8:49 am Post subject: Re: Making a FI Fuel Pressure Gauge and other FI tools |
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If someone has a car which, because of previous tampering with the MPS, won't even run long enough to fine tune the MPS, we do agree it's worth the cost of resetting to a baseline to at least get it running.
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Bobnotch
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Joined: July 06, 2003
Posts: 22431
Location: Kimball, Mi
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| Posted: Thu May 25, 2017 11:01 am Post subject: Re: Making a FI Fuel Pressure Gauge and other FI tools |
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| Donnie strickland wrote: |
As Mike said, the pressure gauge isn't that complicated.
As far as the other tools --
Tach/dwell/volt meter
VOM
Mityvac
Feeler gauges
Etc.
All of these are needed for any Type 3, not just an FI car. |
I'd like to add a timing light, preferably an adjustable one, that allows checking the advance mechanism.
And Donnie is correct, in that I use those same tools on carb cars too, other than the fuel pressure gauge.
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