Onan 7000 - won't run when hot - code 47

[TriumphGuy]

Hi all,
Generator has been finicky lately. Last summer we drove 5000 miles out to Nevada and back (to SC) and the genny didn't have a hiccup in all that heat.
This summer, on our latest trip it wouldn't stay running going down the road. I think it has something to do with the heat ... as we were returning home (about a 4 hour drive) it ran as we drove the morning, stopped for lunch, but then quit about 2pm in the afternoon as we were driving down the interstate.
After that it wouldn't start. Then after about 15 minutes it would start but would quit, throwing a code 47 each time (once it was a code 36).
Looking these up, 47 is ignition related, 36 is "uncommanded stop" (or something like that).

Today I went to visit the coach in storage first thing in the morning. Genny started up on second try, and I let it run for as long as I could before work ... about 25 minutes. No problems.

I've read all sorts of things doing a Google search ... fuel delivery issue (vapor lock) to the board gets hot and malfunctions.

Model is 7HGJAB-900D

Ideas?

[TriumphGuy]

ksg5000 wrote:
First thing I do when my generator works off/on is check the wiring. I clean the connections and use some deoxit or similar - cost nothing. Another common issue sometimes associated with phantom shut downs are flaky fuel pumps and control boards.

Good tip. Can't hurt to clean up the connections, the genny certainly gets a lot of gunk around it with travel / use.

I also thought I might as well change the fuel filters, I think I'm around 450h and realized the svc manual specifies that interval to replace them.

Rick Jay wrote:
TriumphGuy,

How long have you had this generator? What oil are you running in it?

Our Onan 7000 had an issue that if I used the multi-viscosity oil recommended by Onan, it would often shut down while travelling down the road, but only during the hottest days of the summer.

....

That's really interesting ... I thought the low oil was a code in and of itself, but don't remember. Will have to check 🙂

We have owned this coach for almost 3 years now, bought used from the original owner. He was meticulous about maintenance, and we had no issues with the genny the first two years.

Will keep this thread updated with progress. I hadn't found much on the forums about the code 47.

Thanks!

[Rick_Jay]

TriumphGuy,

How long have you had this generator? What oil are you running in it?

Our Onan 7000 had an issue that if I used the multi-viscosity oil recommended by Onan, it would often shut down while travelling down the road, but only during the hottest days of the summer. Keep in mind, we generally travel Pennsylvania and north, so REAL HOT days, compared to down south, are pretty rare. You undoubtedly experience hotter days than we did at the time we had our problem.

Under these hot conditions, the generator would shut-down when the coach went over a rough bridge expansion joint, a moderate pothole or even hard braking. In fact, I even think I remember it shutting down while going around a curve. It would start right back up. It would run fine at any temp when parked. I always "topped off" the oil to the proper level before heading out on the road, so I know it wasn't low on oil.

After observing the phenomenon for the first couple of years of ownership, I surmised the problem was the oil level switch cutting off the ignition because the oil was too thin when HOT. I think I was using 5W-30 at the time. I noticed that as long as it was used above freezing, straight SAE-30 was also acceptable. I picked up a couple of quarts and put them in. That was over 10 years ago and I have not had the problem since. I know that 5W-30 should be equivalent to a 30W when hot, but my generator could tell the difference! LOL 🙂 So, I use straight 30W every time. Spent all last summer in Florida and never had an issue.

Sorry, I never checked for a code. Back then, I was still pretty "green" with this "RV Stuff" and didn't even know the generator would give a code.

Not sure if this is your problem, but if "No ignition signal at P1–15 for 1 continuous second" or "uncommanded stop" includes the situation where the oil level switch cut-off the ignition, maybe it is related.

Good Luck,

~Rick

[ksg5000]

First thing I do when my generator works off/on is check the wiring. I clean the connections and use some deoxit or similar - cost nothing. Another common issue sometimes associated with phantom shut downs are flaky fuel pumps and control boards.

[TriumphGuy]

Here's a direct copy/paste from the service manual (at least what I think is the service manual):

IGNITION FAULT – FAULT CODE 47
WARNING Some genset service procedures present hazards that can result in severe personal injury
or death. Only trained and experienced persons with knowledge of fuels, electricity, and machinery
hazards should perform genset service. See Safety Precautions.
Logic:
HGJAB, C – No ignition signal at P1–15 for 1 continuous second
HGJAA – No ignition signal at P1–5 for 1 continuous second
HGJAD, E, F prior to 2004 – No ignition signal at P1–5 for 1 continuous second
HGJAD, E, F after 2004 in Engine Run Only mode only – No ignition signal at P1–5 for continuous second
Possible Causes: Wire connections, windings, ignition system, generator drive system
Diagnosis & Repair:
1. Verify that Last Fault is FC 47: Yes, continue diagnosis; No, troubleshoot actual last fault.
2. Alternating FC 47 and FC 37: Magneto gap too wide: reset magneto gap, retest.
3. Test Magnetos
A. Disconnect Connector P1.
B. Connect positive(+) meter lead to chassis ground.
C. HGJAA, D, E, F – Measure continuity to negative lead at pin P1–4 and P1–5: replace magnetos as
necessary.
D. HGJAB, C – Measure continuity to negative lead at pin P1–15 and P1–20: replace magnetos as necessary.
4. HGJAD only – Run genset in Engine Run Only and externally excite field with 12 VDC or 24 VDC and
measure main and quadrature winding AC output.
5. Non EFI only – If the genset will not stay running measure genset frequency, quadrature winding and
main winding voltages using Break-Out Tool 420–0603 and Instruction Sheet R1098.
6. Measure AC frequency while changing engine rpm to determine if frequency response matches engine
rpm response: repair damaged generator drive system as necessary.
7. Measure field, quadrature and main winding resistance: clean slip rings, replace brushes, repair harness
and replace rotor or stator as necessary.
8. Measure field, quadrature and main winding resistance to ground: clean slip rings, replace brushes, repair
harness and replace rotor or stator as necessary.
9. Measure field, quadrature and main winding resistance to each other: clean slip rings, replace brushes,
repair harness and replace rotor or stator as necessary.
10. Check brush alignment per PSB-682a.
11. Verify that spark plug cables are secure on spark plugs: reconnect or replace as necessary.
12. Inspect ignition kill leads in harness and at connector P1: repair or replace lead, terminal or pins as necessary.
13. Measure spark plug gap: set gap or replace spark plugs as necessary.
14. Verify ignition spark condition.
15. Inspect spark plug lead, kill lead terminal at magneto and measure magneto air gap: replace terminals,
set gap or replace magnetos as necessary.
16. Dealers contact Distributor for technical support, Distributors contact factory for technical support.