Hi folks,

I'm trying to troubleshoot a sluggishness/hesitation problem with my 84 Crossfire. The car accelerates fine. The sluggishness/hesitation seems most noticeable when I'm reducing speed... trying to maintain a slower speed, the car seems like it's starving of fuel.

I hooked up a fuel pressure gauge (to the same line as fuel filter) and turn the key on (engine off)... I get 12PSI(ish) for a couple seconds then the pressure drops to zero.

The injectors do nothing during this cycle... no spray or drops of fuel come out with the key on engine off.

Is this normal? or should it maintain 12PSI with key on engine off?
If it's supposed to maintain pressure... am I looking at a faulty fuel pump? injector? Pressure regulator?

The FSM states that an injector stuck open would cause the fuel pressure to drop after "setting" (I would think that fuel would be coming out of the injector, though). But that's all I could find that mentions anything about a pressure drop. Doesn't say if it should maintain pressure with Key on Engine off (that I can find...yet).

Previous visual examination of the injectors while engine is running reveals a cone shaped spray from both injectors. I didn't do a pressure test with engine running yet. I wasn't comfortable providing an ignition source to all the fuel that leaked on the floor while installing the gauge.

Has anyone ideas? or had this problem before that can shed some light on it?

Please Help.

 

9-13 psi is the normal stock range.
CFI is a type of tbi, most GM tbi systems don't hold pressure after shut down. I think its a safety thing, if one of those injectors leaked down it could fill up the throttle body w/ gas.
Check your ignition timing, make sure it advances when you rev it.
Check the throttle postion sensor.
Make sure the egr valve isn't staying open when it shouldn't, unplug the vacuum hose & cap it, test drive it to see if it still acts up.
Check the tune up parts too.

 

Thanks XX.

The TPS measures .54v at closed throttle and increases smoothly to 4.9 at WOT.

Tune up parts are new. Cap, Rotor, Plugs, plug wires and PCV.

I checked the EGR valve with a vac pump and I can feel it open and close.... but I will check how it runs with it disconnected this weekend.... and check the timing (gotta buy a timing light).

I'll post the results this weekend. Thanks for replying.

 

I would consider puchasing a tube from crossfire solutuions that allows a FPG between the TB's. But then as a test only run hose from fitting to a FPG taped to outside window. Have passanger read it while engine running under load(WOT) it should maintain 11-12 lbs. If it drops FP you know it needs a F filter at least or a new pump.

 

As fun as that sounds.... that usually results in a punch to my right arm from the wife. Not really a love tap, either.

Did you mean http://www.crossfireinjection.net/catalog.htm ??? ....
They list the item as Out Of Stock... bummer... and a little spensive,

Item Name: '84 Fuel Pressure Assembly (stock)
Item Price: $84.95 (set)
Item SKU: DCS00003

Thanks for the Idea, though. I'll rig something up with a longer hose.... and keep a fire extinguisher handy.

Just picked up a timing light... so I have my weekend pretty much planned under the hood... so far.

 

I picked up a craftsman timing light with the adjustment dial.
The timing advances with throttle increase and seems to back off ok... BUT
According to the instructions with the timing light... the the timing is set at about 22deg BTDC (EST connected), at 600-700 RPM and engine temp at about 190deg.

To double check... I tried disconnecting the EST... or at least what I think was the EST (4 wire plug that comes out the back side of the distributor), but the car wouldn't start.. no fuel spraying from the injectors. Re-connect it and it starts fine.

Should I back it off to 6-10 deg BTDC... then try to see if it'll start with what I think is the EST disconnected?... hmmm... no fuel would still an issue, though.

Still working on a remote view fuel pressure gauge to test it under load.

Also, I did notice it seems to hesitate/sluggish when accelerating from a stop, too. I guess I got used to initially putting my foot into it to get past the hesitation and then ease up.

Pic 1 - Timing light mark and light setting with EST connected.
Pic 2 - assumed EST connector. Car won't start with this disconnected.

 

OK... I think I found the EST wire.... kinda right near the brake booster... brown/blk wire near the MAP sensor, correct? (If so, Thanks Chilton manual... the FSM didn't help in locating it)

 

Yeah, thats it.

 

DIRTY INJECTORS CAUSE ALL TYPES OF PROBLEMS; WHILE YOU HAVE THE TIMING LITE CONNECTED;REMOVED THE AIR CLEANER TOP START THE ENGINE AND WITH THE TIMING LITE, FLASH THE LITE AT THE INJECTORS. THE FUEL SPRAY OUT OF THE INJECTORS SHOULD BE A MISTY CONE SHAPED SPRAY,CHECK THEM BOTH . IF THERE IS NOT A NICE SPRAY WITH A CONNICAL CONE SHAPE ,DIRTY OR BAD INJECTORS. NOT SAYING THAT WOULD BE YOUR PROBLEM BUT ITS A QUICK EASY CHECK. TIMING DOESN'T NORMALLY CHANGE BY ITSELF. IF THE CAR WAS RUNNING FINE AND GRADUALLY GOT WORSE AND NO ONE WAS PLAYING UNDER THE HOOD THE TIMING IS PROBABLY OK. THE TIMING LITE YOU HAVE WILL CHECK THE TIMING WITH NO PROBLEM. LEAVE THE ADVANCE SETTING AT 0 AND CHECK YOUR TIMING AS NORMAL. THE ADVANCE SETTING IS USED TO SET TIMING AT A HIGHLY ADVANCED SETTING.RACE ENGINE APPLICATION,VERY FEW STREET ENGINES REQUIRE THIS SETTING. IF YOUR ATTEMPTING TO SET YOUR TIMING AT A HIGHER SETTING THEN WHAT SHOWS ON THE TIMING TAB,THEN YOU WOULD SET THE ADVANCE SETTING ON THE LITE TO YOUR DESIRED SETTING,LETS SAY 20 DEGREES. SET IT AT 20 DEGREES THEN WHEN TIMING, SET THE TIMING MARK TO 0 DEGREES ON THE TIMING TAB ON THE ENGINE. WITH THE TIMING SET TO 0 DEGREES ON THE TAB YOUR ACTUALL TIMING WOULD BE 20 DEGREES. AGAIN I GOT CARRIED AWAY,CHECK YOUR INJECTORS,JUST MIGHT BE THE PROBLEM????

 

I re-checked the timing with the correct EST wire disconnected... and verified it's set to 6deg BTDC.... so it doesn't look like it's a timing issue.

After re-connecting the fuel pressure gauge and starting the car, the pressure stayed at 11.5 PSI during idle and while test driving it... so it doesn't seem to be a fuel pump issue.

Both injectors show a cone shaped spray pattern... they seem like they make a lot of noise, though... very noticeable ticking.

I hooked up the laptop and WINADL cable w/10K ohm resistor... and took it for a test drive around the block. It had a Spark sensor 42 and 43 code stored... but I think that was from my first attempt at checking the timing and disconnecting the wrong connector(s).

I captured the data and looked thru it... but no luck deciphering anything meaningful... to me, anyway.

Is anyone on here willing to look at the data and see if anything jumps out as being a problem? (file attached)

In addition to the hesitation issue... I noticed there seems to be an idle fluctuation in the RPM's... not enough for the tachometer to change.... but I can hear it fluctuating (hunting?)... while in gear sitting at a stop light and in park.

Depending on the ALDL response... Not sure what the next step should be... rebuild the injectors?... or have them rebuilt/cleaned? Couldn't hurt anything... except my pocket.

 

Id check for vacuum leaks, esp. around the throttle linkage (they get loose) & the top gasket of the intake.
I couldn't get your file to come up.

 

Thanks XXF.

I'll do that sometime early this week.

It's been one of those weekends where I did a lot on the car... and nothing accomplished.

I just fixed the attachment... I think.

 

If you want an easy way to test fuel pressure on the fly, do this: Remove your crossover tube between the throttle bodies. Take it to a local hose and tubing shop and have them weld in a fitting. Have them also crimp on a corresponding fitting onto a piece of fuel injection hose.

Now, anytime you want to test your pressure, no need to crawl under the car....and you're reading it from the most crucial place. I did this on my old CFI and it cost me about $25 to have done. Money well spent. Here's what it looked like.



NOW....connect a longer piece of hose to a 0-15 psi guage, and tape it to the windshield. Now you can test on the fly.

 

MY INJECTORS SOUNDED LIKE LIFTERS CLATERING WHEN I FIRST GOT IT,AND RAN A LITTLE CRAPPY. THERE WAS A OIL LEAK,INTAKE TO BLOCK.SO I PULLED THE INTAKE TO REPAIR LEAK. WHILE I HAD THE INTAKE OFF,I DID A COMPLETE REBUILD ON THE THROTTLE BODIES, NOT MUCH,JUST A FEW GASKETS AND FUEL PRESSURE REG. THEN I FOLLOWED THE F.S.M. AND ADJUSTED EVERYTHING AS TO THE SERVICE MANUAL. IT RAN LIKE A NEW ONE. DON'T KNOW IF IT WAS THE INJECTORS,THE CLEANING,THE FUEL PRESSURE REG. ALL THE SETTINGS,OR A COMBINATION OF ALL. BUT EITHER WAY,FIGURED IT NEEDED IT ANYWAY AFTER 25 YEARS. OH! AND THE INJECTORS WERE STILL CLICKING, NOT AS LOUD AS OLD BUT STILL CLACKING. JUST MY 2 CENTS. GOOD LUCK

 

diversified crossfire solutions sells that modded hard line.

 

Sifting through the data... I noticed the RAW:TPS, RAW:O2, SENSOR:TPS and SENSOR:O2 have some pretty wide fluctuations.

Do the "Sensor TPS" and "Sensor O2" numbers mean anything? I thought the TPS only does .54v-5vDC.... but I see numbers as high as 55.7.

the O2 sensor has fluctuations like .774, .106... then .818 while doing the same speed...

 

When I open the columns are not aligned. If TPS is in voltage it will show .52 closed and 4.5 WOT. MAP will be like .50 to 5.0 (WOT). BLM is the fuel trim and the one you want to note. Should be like 124-132 128 being neutral or perfect. Watch for a BLM trend high or low. O2 sensor will swing and is normal to see .200-.800. That is how it functions(swing over stoich). 02 WOT I recall is steady and can be an imperfect indicator of lean rich. Same when in OL I recall it does not swing and is an indicator. You should be able to see malf codes as well?? If any.

 

Thanks Rohn.

BLM has a low of 125 and a high of 139.

MALF Code 43 was present... but like I stated earlier... I think that was from an uneducated failed attempt at finding and disconnecting the EST wire to check base timing. I'll have to clear that and recheck things.

The file looks good when opened with a spreadsheet program.
I tried to clean it up some by keeping only the sensor data and removed the RAW data. Hopefully I didn't cut out anything important.

 

Good info. Just an FYI. Caps lock is considered yelling. And

 

This maybe a dumb question but what is the EST wire and why must it be disconnected before you set the timming. I ask because I set the timing this summer and never disconnected any EST wire does that mean my timming is off?