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1991 Buick Reatta no start.


ReeRee
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Just picked up a 91 reatta (L27 4t60e) a couple days ago and it started to stutter under load while driving. Replaced the fuel filter because it was clogged and replaced coil packs and plug wires and went on a test drive. Stutter improved but it still misfired a couple of times. A/C was blowing thru the defroster and I found I had disconnected a vacuum line along the firewall so I put it back on. Started the car up again and it idled fine for a few minutes and A/C blew thru the correct vents but engine died when I attempted to shift into reverse now the engine cranks but won't start and the A/C is blowing thru defroster again. No codes in the diag menu. Any help on what to look for would be appreciated

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Still sounds like low or no fuel pressure. If the car sat for a long time it could have bad gas or a rusty tank plugging up the filter. Or the fuel pump finally went out. Could also be a bad fuel pressure regulator.

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3 hours ago, ReeRee said:

... engine died when I attempted to shift into reverse now the engine cranks but won't start and the A/C is blowing thru defroster again. No codes in the diag menu. Any help on what to look for would be appreciated

Air blowing through the defroster vents is the default when no vacuum is present. Without engine running there is no vacuum so what you describe is normal operation.

 

3 hours ago, ReeRee said:

replaced coil packs and plug wires and went on a test drive.

Did you replace the Ignition Control Module (ICM) when you replaced the coils? Low fuel pressure, bad crankshaft position sensor and ICM won't set a code in diagnostics. How-to guides for testing all of them are on my website.

 

 

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Posted (edited)

No I did not replace the icm because I hadn't noticed any ooze. Just ran a in-line ignition spark tester on cylinder 1 and 3 and its showing I no longer have spark.

 

I also noticed this vacuum line is dry rotted(in picture below)16553431685763193753494414504508.jpg.9a73a11f7aee1d48b5d6086e0ef69134.jpg

Edited by ReeRee (see edit history)
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I would worry about the no spark problem first. The vacuum lines aren't keeping the engine from starting. When you do replace the rotted vacuum line, be careful with the part they plug in to. It is easy to break. 

 

The ICM can go bad without any sign of anything wrong on the outside. The goo on the outside is a good indicator it is going bad but isn't always present when the ICM is bad. If you have a good ICM to try you should do that. If you don't have an ICM, and you have good troubleshooting skills, you can try to determine if the problem is the ICM or crankshaft position sensor using the tests I mentioned above.

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L27 is probably the triple coils so the symptoms of failure of the ICM may be different. Definitely do the crank sensor tests as per Ronnie’s site. Without spark, nothing else matters

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Need to get a multimeter checked the fuses in the center console thru the passenger side and they all looked good. Will update once I've ran the tests.

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Posted (edited)

I believe I may have found my issue. I crawled under the car this morning and went to check on the connector for the cps and the sensor is loose in the bracket and is able to wiggle around. Would I be able to reposition the sensor or would it be better to replace it?

 

Also the new icm has 14 pins but the connector only has 13. I know on the wiring diagram K has nothing on it so should the new icm still work?

Edited by ReeRee (see edit history)
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If the CPS could move around enough to fail starting the engine, it is likely damaged. The only way to know for sure is to examine it and then you have already done most of the work to replace it. I believe the ICM for almost all late style 3800 Delco style ignitions will work. What engine model years does it cover?

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Posted (edited)

Replace cps and vehicle starts now. Ran ok on the way to the store but died while braking to pull in once it warmed up. Started again and dies when coming to stops and now also dies idling in park with no throttle but held rpms around 2k with some throttle. 

 

Now throws e042 and b132

Edited by ReeRee (see edit history)
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Your last two posts seem to conflict with each other. One said it wouldn't start after replacing the CPS. The other says it did. Try unplugging the MAF senor and see what effect that has. Neither code you mentioned will have a noticeable effect on the way the engine starts or runs.

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Posted (edited)

Ok to clarify on the last 2 post I had installed a new sensor but the harmonic balancer had a bent blade so it immediately broke the new sensor.

 

Got a second new sensor and a new harmonic balancer and the engine starts now.  Idle seems the same with the MAF connected/ddisconnected. Died when giving throttle with MAF disconnected.

 

There also seems to be a sort of rattle from the engine.

 

This is the icm I picked up. It says it's a 20 pin but it actually has 14. Is the 5th pin from the left K redundant?

https://www.oreillyauto.com/detail/c/masterpro-ignition/ignition---tune-up/ignition-module-control-unit-ignitor/9331d0e7f826/masterpro-ignition-20-terminal-ignition-control-module/opi0/27094/v/a/2652/automotive-car-1991-buick-reatta?pos=0

Edited by ReeRee (see edit history)
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The ICM you purchased seems to be the correct one for your '91 although I have never heard of that brand. I assume you have it bolted down good. It grounds through the mounting plate under it. You said earlier that you had some vacuum leaks. You should fix them and check fuel pressure if you haven't already done so done so.

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7 hours ago, ReeRee said:

This is the icm I picked up. It says it's a 20 pin but it actually has 14. Is the 5th pin from the left K redundant?

As you can see in the schematic below, the ICM has no connection to the 5th pin (K).

 

cpstutorial-2.jpg

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I had a Fiero that had the same problem, engine dies when coming to a stop. Turned out the TPS had a bad connection and was going to zero on a stop but read normally otherwise. Torque Pro can display the TPS (.38-.42v at idle, over 4.0v at WOT.)

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Posted (edited)

Cleaned throttle body a reinstalled did pressure test and it showed 42 psi when key was turned on. Running at idle showing 36 psi. When keyed on then back off fuel pressure maintained at 42psi for several minutes no noticeable loss of pressure.

 

Car idling steady while cold and then idles at operating temp for a little while. No fuel pressure drop when engine stalls.

Edited by ReeRee (see edit history)
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Have you scrolled through diagnostics looking at the various sensors while it is idling? The TPS was asked about previously. Since you don't seem to be getting codes, the ignition would be suspect, but you have covered much of that previously. Is there a pattern to the length of time it will idle before dying, such as two minutes, or perhaps a specific engine temperature threshold?

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Posted (edited)

I looked at ed01 which I saw was the tps sensor reading on another post and it reads .42v at idle and 4.3 at WOT. Engine idles and runs fine while cold and will idle ok once warm for a few minutes. Was looking at a few of those going to try again latter once its cooled off. When throttle is applied rpm tend to hang around 800-900 then fall down between 600-700. 

 

Videos here:

 

 

 

Edited by ReeRee (see edit history)
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Your tachometer jumping around might be an indication of what is causing your problem. It doesn't seem to be jumping in unison with the engine RPM. The engine seems to be following what the tach is doing.

 

The way it died in the first video sorta sounded like it was out of time and blowing compression back through the intake. The last time I heard that sound was when my Crankshaft Position Sensor went bad and left me stranded on the side of the road. A bad CPS could also account for the tach jumping around erratically at idle to.

 

 

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Nothing in particular jumps out, although the oil pressure sender appears to be bad. Unlikely to be the cause of the stalling, but it is pegged even with key on and engine off so something is amiss there. It also enables the fuel pump, although there are redundant paths for that. If this behavior is repeatable, I know it would be tedious, but I suggest watching various sensors real time while idling until it quits. TPS is as good a place to start as any. Just leave it on ED01 and watch it for a while, same for a few others, MAF I usually see 4-6gr/sec at idle, ignition timing, should be around 20deg or a little more, IAC counts (variable), maybe the O2 sensor (variable) and fuel integrator (around 128). The way it quits sounds like ignition, no real bobble like running out of fuel, but it is quick.

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Posted (edited)

Bought oil pressure sensor and only reading 23 psi at idle. Still need to check sensors while stalling. Sensor readings at idle are below

 

ED01: .42-.44

ED04: .54

ED06: 5.5-5.8

ED07: .45

ED08: 19-24

ED10: 13.6-13.8

ED11: 800

ED12: 0

ED16: 0

ED17: 273

ED18: 49-65

ED19: 128

ED20: 134

ED21: 6.4

ED22: 51

ED23: 44

ED24: 675

ED25: 17

ED26: 14.3

ED27-ED30: 0

ED31: 0110

ED98: 13

ED99: 1484

Edited by ReeRee (see edit history)
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Interesting. Apparently the 91 has an extended scanning range. My 90 only extends to ED23. 
 

Most things look relatively normal but a couple things seem unusual to me. 
ED08 spark advance is unusual for it to move around over that range at idle. Usually I see a stable number around 20 or a bit more but not moving around by five degrees.

ED18 cross counts. Generally higher number is better but I have never seen numbers that high, ever, especially at idle. 
I don’t know exactly what that means but seems unusual

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I had thought ed08 was a bit odd as well the only part of the ignition system I haven't replaced is the actual plugs so I'm planning to check the condition of them. I'm also concerned about the injectors being gummed up at not atomizing the fuel correctly. Wanting to find out what is causing the rattling from the engine bay as well and I'm concerned it's possibly due to the lower oil pressure and how it might affect the bearings. Does anybody know if the 3800 are prone to valve seats going out as well because it backfires under load occasionally and it was mentioned that it may be out of time.

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On 6/27/2022 at 12:22 PM, ReeRee said:

Was looking at a few of those going to try again latter once its cooled off. When throttle is applied rpm tend to hang around 800-900 then fall down between 600-700

I would go old school to help determine what is going on. If you have a timing light, hook it up and connect it to one of the spark plug wires. Then instead of pointing it at the harmonic balancer like you would to set timing, turn the strobe light toward you so you can watch it flash as the engine starts to die. If the strobe light continues to flash steady as the RPM goes down and the engine dies the ignition MAY not be at the problem. If the strobe light is erratic and/or shuts off as the engine comes to a stop you can be pretty certain that something is going on with the ignition system.

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I don't know of any issue with valves or valve seats on the 3800. A rattle at idle that disappears with rpm may be the harmonic balancer. Since it was removed and replaced, was it examined closely for cracking in the rubbery face of the balancer? A relatively common failure from heat and miles that sounds like a bad bearing. How is the oil pressure being determined? I believe there are two different sending units depending on year where the base oil pressure is higher in later years so the indication may be off. I don't know this for a fact yet.

 

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I was curious so I looked at the sending unit part number for a 90 and 91 Reatta and they are indeed different. The OEM crossover numbers are different as well. Since they look exactly the same, my assumption is a different expected pressure range to get a similar display on the dash?

In this case, Standard Motor Products is PS246 for 91 and PS258 for 90 and earlier.

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Harmonic balancer does appear to have slight wobble. New oil pressure sensor is a Duralast PS227. Oil pressure readings taken thru BD71 read in the 40s yesterday at cold idle. Going to be taking the harmonic balancer back off anyways but the box it had came in was handle a bit rough and the new CPS had a small part of the molding broken off. The dust shield also was in rough condition and looks like it was melted by friction with the old harmonic balancer. Will post pics once I have them. Also noticing it's smoking a bit in the rear of the engine bay and read some posts on the EGR and cleaning it but it also has a powersteering leak so I believe it may be burning some of that off as well

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Just as an idea

check all your wiring especially if its a higher milage car

we had a low milage used 05 lesabre daily driver after awhile the wiring going to the ICM

was going bad very intermittent to the point of sometimes shutting the car off

they wired in a new plug and wiring and it fixed it

just an idea  

 

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1 hour ago, ReeRee said:

Harmonic balancer does appear to have slight wobble.

Make certain you have the correct harmonic balancer. I believe your '91 should have a balancer with a tapered fit to the crankshaft. Installing an earlier balance that doesn't have a tapered fit would probably wobble on the '91 crankshaft that has a taper on it. I don't know that it would actually fit on your crankshaft but it is worth checking when you have it off.

 

 

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20 psi at hot idle is fine. Are you using 10w-30 synthetic ? I remember Herb Adams saying "at idle you do not need any oil pressure", believe switch is set to 6 psi.

C (40 psi relief) and L (60psi relief) are different. L sensor in a C engine will read low.

If an engine drops revs suddenly it can emit a puff of HC. 3800s have a DFCO that keeps the revs up for a moment.

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  • Ronnie changed the title to 1991 Buick Reatta no start.

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